feat(reader): 🎉 Add support for multi-file DBML loading

* Implement directory reading for DBML files.
* Merge schemas and tables from multiple files.
* Add tests for multi-file loading and merging behavior.
* Enhance file discovery and sorting logic.

.github/workflows/integration-tests.yml

@@ -46,6 +46,11 @@ jobs:
     - name: Download dependencies
       run: go mod download
 
+    - name: Install PostgreSQL client
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y postgresql-client
+
     - name: Initialize test database
       env:
         PGPASSWORD: relspec_test_password

README.md

@@ -85,6 +85,29 @@ RelSpec includes a powerful schema validation and linting tool:
 ## Use of AI
 [Rules and use of AI](./AI_USE.md)
 
+## User Interface
+
+RelSpec provides an interactive terminal-based user interface for managing and editing database schemas. The UI allows you to:
+
+- **Browse Databases** - Navigate through your database structure with an intuitive menu system
+- **Edit Schemas** - Create, modify, and organize database schemas
+- **Manage Tables** - Add, update, or delete tables with full control over structure
+- **Configure Columns** - Define column properties, data types, constraints, and relationships
+- **Interactive Editing** - Real-time validation and feedback as you make changes
+
+The interface supports multiple input formats, making it easy to load, edit, and save your database definitions in various formats.
+
+<p align="center" width="100%">
+<img  src="./assets/image/screenshots/main_screen.jpg"> 
+</p>
+<p align="center" width="100%">
+<img  src="./assets/image/screenshots/table_view.jpg"> 
+</p>
+<p align="center" width="100%">
+<img src="./assets/image/screenshots/edit_column.jpg"> 
+</p>
+
+
 ## Installation
 
 ```bash
@@ -95,6 +118,55 @@ go install -v git.warky.dev/wdevs/relspecgo/cmd/relspec@latest
 
 ## Usage
 
+### Interactive Schema Editor
+
+```bash
+# Launch interactive editor with a DBML schema
+relspec edit --from dbml --from-path schema.dbml --to dbml --to-path schema.dbml
+
+# Edit PostgreSQL database in place
+relspec edit --from pgsql --from-conn "postgres://user:pass@localhost/mydb" \
+             --to pgsql --to-conn "postgres://user:pass@localhost/mydb"
+
+# Edit JSON schema and save as GORM models
+relspec edit --from json --from-path db.json --to gorm --to-path models/
+```
+
+The `edit` command launches an interactive terminal user interface where you can:
+- Browse and navigate your database structure
+- Create, modify, and delete schemas, tables, and columns
+- Configure column properties, constraints, and relationships
+- Save changes to various formats
+- Import and merge schemas from other databases
+
+### Schema Merging
+
+```bash
+# Merge two JSON schemas (additive merge - adds missing items only)
+relspec merge --target json --target-path base.json \
+              --source json --source-path additions.json \
+              --output json --output-path merged.json
+
+# Merge PostgreSQL database into JSON, skipping specific tables
+relspec merge --target json --target-path current.json \
+              --source pgsql --source-conn "postgres://user:pass@localhost/source_db" \
+              --output json --output-path updated.json \
+              --skip-tables "audit_log,temp_tables"
+
+# Cross-format merge (DBML + YAML → JSON)
+relspec merge --target dbml --target-path base.dbml \
+              --source yaml --source-path additions.yaml \
+              --output json --output-path result.json \
+              --skip-relations --skip-views
+```
+
+The `merge` command combines two database schemas additively:
+- Adds missing schemas, tables, columns, and other objects
+- Never modifies or deletes existing items (safe operation)
+- Supports selective merging with skip options (domains, relations, enums, views, sequences, specific tables)
+- Works across any combination of supported formats
+- Perfect for integrating multiple schema definitions or applying patches
+
 ### Schema Conversion
 
 ```bash

cmd/relspec/merge.go

@@ -0,0 +1,433 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"git.warky.dev/wdevs/relspecgo/pkg/merge"
+	"git.warky.dev/wdevs/relspecgo/pkg/models"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/bun"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/dbml"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/dctx"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/drawdb"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/drizzle"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/gorm"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/graphql"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/json"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/pgsql"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/prisma"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/typeorm"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/yaml"
+	"git.warky.dev/wdevs/relspecgo/pkg/writers"
+	wbun "git.warky.dev/wdevs/relspecgo/pkg/writers/bun"
+	wdbml "git.warky.dev/wdevs/relspecgo/pkg/writers/dbml"
+	wdctx "git.warky.dev/wdevs/relspecgo/pkg/writers/dctx"
+	wdrawdb "git.warky.dev/wdevs/relspecgo/pkg/writers/drawdb"
+	wdrizzle "git.warky.dev/wdevs/relspecgo/pkg/writers/drizzle"
+	wgorm "git.warky.dev/wdevs/relspecgo/pkg/writers/gorm"
+	wgraphql "git.warky.dev/wdevs/relspecgo/pkg/writers/graphql"
+	wjson "git.warky.dev/wdevs/relspecgo/pkg/writers/json"
+	wpgsql "git.warky.dev/wdevs/relspecgo/pkg/writers/pgsql"
+	wprisma "git.warky.dev/wdevs/relspecgo/pkg/writers/prisma"
+	wtypeorm "git.warky.dev/wdevs/relspecgo/pkg/writers/typeorm"
+	wyaml "git.warky.dev/wdevs/relspecgo/pkg/writers/yaml"
+)
+
+var (
+	mergeTargetType    string
+	mergeTargetPath    string
+	mergeTargetConn    string
+	mergeSourceType    string
+	mergeSourcePath    string
+	mergeSourceConn    string
+	mergeOutputType    string
+	mergeOutputPath    string
+	mergeOutputConn    string
+	mergeSkipDomains   bool
+	mergeSkipRelations bool
+	mergeSkipEnums     bool
+	mergeSkipViews     bool
+	mergeSkipSequences bool
+	mergeSkipTables    string // Comma-separated table names to skip
+	mergeVerbose       bool
+)
+
+var mergeCmd = &cobra.Command{
+	Use:   "merge",
+	Short: "Merge database schemas (additive only - adds missing items)",
+	Long: `Merge one database schema into another. Performs additive merging only:
+adds missing schemas, tables, columns, and other objects without modifying
+or deleting existing items.
+
+The target database is loaded first, then the source database is merged into it.
+The result can be saved to a new format or updated in place.
+
+Examples:
+  # Merge two JSON schemas
+  relspec merge --target json --target-path base.json \
+                --source json --source-path additional.json \
+                --output json --output-path merged.json
+
+  # Merge from PostgreSQL into JSON
+  relspec merge --target json --target-path mydb.json \
+                --source pgsql --source-conn "postgres://user:pass@localhost/source_db" \
+                --output json --output-path combined.json
+
+  # Merge DBML and YAML, skip relations
+  relspec merge --target dbml --target-path schema.dbml \
+                --source yaml --source-path tables.yaml \
+                --output dbml --output-path merged.dbml \
+                --skip-relations
+
+  # Merge and save back to target format
+  relspec merge --target json --target-path base.json \
+                --source json --source-path patch.json \
+                --output json --output-path base.json`,
+	RunE: runMerge,
+}
+
+func init() {
+	// Target database flags
+	mergeCmd.Flags().StringVar(&mergeTargetType, "target", "", "Target format (required): dbml, dctx, drawdb, graphql, json, yaml, gorm, bun, drizzle, prisma, typeorm, pgsql")
+	mergeCmd.Flags().StringVar(&mergeTargetPath, "target-path", "", "Target file path (required for file-based formats)")
+	mergeCmd.Flags().StringVar(&mergeTargetConn, "target-conn", "", "Target connection string (required for pgsql)")
+
+	// Source database flags
+	mergeCmd.Flags().StringVar(&mergeSourceType, "source", "", "Source format (required): dbml, dctx, drawdb, graphql, json, yaml, gorm, bun, drizzle, prisma, typeorm, pgsql")
+	mergeCmd.Flags().StringVar(&mergeSourcePath, "source-path", "", "Source file path (required for file-based formats)")
+	mergeCmd.Flags().StringVar(&mergeSourceConn, "source-conn", "", "Source connection string (required for pgsql)")
+
+	// Output flags
+	mergeCmd.Flags().StringVar(&mergeOutputType, "output", "", "Output format (required): dbml, dctx, drawdb, graphql, json, yaml, gorm, bun, drizzle, prisma, typeorm, pgsql")
+	mergeCmd.Flags().StringVar(&mergeOutputPath, "output-path", "", "Output file path (required for file-based formats)")
+	mergeCmd.Flags().StringVar(&mergeOutputConn, "output-conn", "", "Output connection string (for pgsql)")
+
+	// Merge options
+	mergeCmd.Flags().BoolVar(&mergeSkipDomains, "skip-domains", false, "Skip domains during merge")
+	mergeCmd.Flags().BoolVar(&mergeSkipRelations, "skip-relations", false, "Skip relations during merge")
+	mergeCmd.Flags().BoolVar(&mergeSkipEnums, "skip-enums", false, "Skip enums during merge")
+	mergeCmd.Flags().BoolVar(&mergeSkipViews, "skip-views", false, "Skip views during merge")
+	mergeCmd.Flags().BoolVar(&mergeSkipSequences, "skip-sequences", false, "Skip sequences during merge")
+	mergeCmd.Flags().StringVar(&mergeSkipTables, "skip-tables", "", "Comma-separated list of table names to skip during merge")
+	mergeCmd.Flags().BoolVar(&mergeVerbose, "verbose", false, "Show verbose output")
+}
+
+func runMerge(cmd *cobra.Command, args []string) error {
+	fmt.Fprintf(os.Stderr, "\n=== RelSpec Merge ===\n")
+	fmt.Fprintf(os.Stderr, "Started at: %s\n\n", getCurrentTimestamp())
+
+	// Validate required flags
+	if mergeTargetType == "" {
+		return fmt.Errorf("--target format is required")
+	}
+	if mergeSourceType == "" {
+		return fmt.Errorf("--source format is required")
+	}
+	if mergeOutputType == "" {
+		return fmt.Errorf("--output format is required")
+	}
+
+	// Validate and expand file paths
+	if mergeTargetType != "pgsql" {
+		if mergeTargetPath == "" {
+			return fmt.Errorf("--target-path is required for %s format", mergeTargetType)
+		}
+		mergeTargetPath = expandPath(mergeTargetPath)
+	} else if mergeTargetConn == "" {
+
+		return fmt.Errorf("--target-conn is required for pgsql format")
+
+	}
+
+	if mergeSourceType != "pgsql" {
+		if mergeSourcePath == "" {
+			return fmt.Errorf("--source-path is required for %s format", mergeSourceType)
+		}
+		mergeSourcePath = expandPath(mergeSourcePath)
+	} else if mergeSourceConn == "" {
+		return fmt.Errorf("--source-conn is required for pgsql format")
+	}
+
+	if mergeOutputType != "pgsql" {
+		if mergeOutputPath == "" {
+			return fmt.Errorf("--output-path is required for %s format", mergeOutputType)
+		}
+		mergeOutputPath = expandPath(mergeOutputPath)
+	}
+
+	// Step 1: Read target database
+	fmt.Fprintf(os.Stderr, "[1/3] Reading target database...\n")
+	fmt.Fprintf(os.Stderr, "      Format: %s\n", mergeTargetType)
+	if mergeTargetPath != "" {
+		fmt.Fprintf(os.Stderr, "      Path:   %s\n", mergeTargetPath)
+	}
+	if mergeTargetConn != "" {
+		fmt.Fprintf(os.Stderr, "      Conn:   %s\n", maskPassword(mergeTargetConn))
+	}
+
+	targetDB, err := readDatabaseForMerge(mergeTargetType, mergeTargetPath, mergeTargetConn, "Target")
+	if err != nil {
+		return fmt.Errorf("failed to read target database: %w", err)
+	}
+	fmt.Fprintf(os.Stderr, "      ✓ Successfully read target database '%s'\n", targetDB.Name)
+	printDatabaseStats(targetDB)
+
+	// Step 2: Read source database
+	fmt.Fprintf(os.Stderr, "\n[2/3] Reading source database...\n")
+	fmt.Fprintf(os.Stderr, "      Format: %s\n", mergeSourceType)
+	if mergeSourcePath != "" {
+		fmt.Fprintf(os.Stderr, "      Path:   %s\n", mergeSourcePath)
+	}
+	if mergeSourceConn != "" {
+		fmt.Fprintf(os.Stderr, "      Conn:   %s\n", maskPassword(mergeSourceConn))
+	}
+
+	sourceDB, err := readDatabaseForMerge(mergeSourceType, mergeSourcePath, mergeSourceConn, "Source")
+	if err != nil {
+		return fmt.Errorf("failed to read source database: %w", err)
+	}
+	fmt.Fprintf(os.Stderr, "      ✓ Successfully read source database '%s'\n", sourceDB.Name)
+	printDatabaseStats(sourceDB)
+
+	// Step 3: Merge databases
+	fmt.Fprintf(os.Stderr, "\n[3/3] Merging databases...\n")
+
+	opts := &merge.MergeOptions{
+		SkipDomains:   mergeSkipDomains,
+		SkipRelations: mergeSkipRelations,
+		SkipEnums:     mergeSkipEnums,
+		SkipViews:     mergeSkipViews,
+		SkipSequences: mergeSkipSequences,
+	}
+
+	// Parse skip-tables flag
+	if mergeSkipTables != "" {
+		opts.SkipTableNames = parseSkipTables(mergeSkipTables)
+		if len(opts.SkipTableNames) > 0 {
+			fmt.Fprintf(os.Stderr, "      Skipping tables: %s\n", mergeSkipTables)
+		}
+	}
+
+	result := merge.MergeDatabases(targetDB, sourceDB, opts)
+
+	// Update timestamp
+	targetDB.UpdateDate()
+
+	// Print merge summary
+	fmt.Fprintf(os.Stderr, "      ✓ Merge complete\n\n")
+	fmt.Fprintf(os.Stderr, "%s\n", merge.GetMergeSummary(result))
+
+	// Step 4: Write output
+	fmt.Fprintf(os.Stderr, "\n[4/4] Writing output...\n")
+	fmt.Fprintf(os.Stderr, "      Format: %s\n", mergeOutputType)
+	if mergeOutputPath != "" {
+		fmt.Fprintf(os.Stderr, "      Path:   %s\n", mergeOutputPath)
+	}
+
+	err = writeDatabaseForMerge(mergeOutputType, mergeOutputPath, "", targetDB, "Output")
+	if err != nil {
+		return fmt.Errorf("failed to write output: %w", err)
+	}
+
+	fmt.Fprintf(os.Stderr, "      ✓ Successfully written merged database\n")
+	fmt.Fprintf(os.Stderr, "\n=== Merge complete ===\n")
+
+	return nil
+}
+
+func readDatabaseForMerge(dbType, filePath, connString, label string) (*models.Database, error) {
+	var reader readers.Reader
+
+	switch strings.ToLower(dbType) {
+	case "dbml":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for DBML format", label)
+		}
+		reader = dbml.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "dctx":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for DCTX format", label)
+		}
+		reader = dctx.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "drawdb":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for DrawDB format", label)
+		}
+		reader = drawdb.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "graphql":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for GraphQL format", label)
+		}
+		reader = graphql.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "json":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for JSON format", label)
+		}
+		reader = json.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "yaml":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for YAML format", label)
+		}
+		reader = yaml.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "gorm":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for GORM format", label)
+		}
+		reader = gorm.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "bun":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for Bun format", label)
+		}
+		reader = bun.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "drizzle":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for Drizzle format", label)
+		}
+		reader = drizzle.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "prisma":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for Prisma format", label)
+		}
+		reader = prisma.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "typeorm":
+		if filePath == "" {
+			return nil, fmt.Errorf("%s: file path is required for TypeORM format", label)
+		}
+		reader = typeorm.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "pgsql":
+		if connString == "" {
+			return nil, fmt.Errorf("%s: connection string is required for PostgreSQL format", label)
+		}
+		reader = pgsql.NewReader(&readers.ReaderOptions{ConnectionString: connString})
+	default:
+		return nil, fmt.Errorf("%s: unsupported format '%s'", label, dbType)
+	}
+
+	db, err := reader.ReadDatabase()
+	if err != nil {
+		return nil, err
+	}
+
+	return db, nil
+}
+
+func writeDatabaseForMerge(dbType, filePath, connString string, db *models.Database, label string) error {
+	var writer writers.Writer
+
+	switch strings.ToLower(dbType) {
+	case "dbml":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for DBML format", label)
+		}
+		writer = wdbml.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "dctx":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for DCTX format", label)
+		}
+		writer = wdctx.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "drawdb":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for DrawDB format", label)
+		}
+		writer = wdrawdb.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "graphql":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for GraphQL format", label)
+		}
+		writer = wgraphql.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "json":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for JSON format", label)
+		}
+		writer = wjson.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "yaml":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for YAML format", label)
+		}
+		writer = wyaml.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "gorm":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for GORM format", label)
+		}
+		writer = wgorm.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "bun":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for Bun format", label)
+		}
+		writer = wbun.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "drizzle":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for Drizzle format", label)
+		}
+		writer = wdrizzle.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "prisma":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for Prisma format", label)
+		}
+		writer = wprisma.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "typeorm":
+		if filePath == "" {
+			return fmt.Errorf("%s: file path is required for TypeORM format", label)
+		}
+		writer = wtypeorm.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	case "pgsql":
+		writer = wpgsql.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+	default:
+		return fmt.Errorf("%s: unsupported format '%s'", label, dbType)
+	}
+
+	return writer.WriteDatabase(db)
+}
+
+func expandPath(path string) string {
+	if len(path) > 0 && path[0] == '~' {
+		home, err := os.UserHomeDir()
+		if err == nil {
+			return filepath.Join(home, path[1:])
+		}
+	}
+	return path
+}
+
+func printDatabaseStats(db *models.Database) {
+	totalTables := 0
+	totalColumns := 0
+	totalConstraints := 0
+	totalIndexes := 0
+
+	for _, schema := range db.Schemas {
+		totalTables += len(schema.Tables)
+		for _, table := range schema.Tables {
+			totalColumns += len(table.Columns)
+			totalConstraints += len(table.Constraints)
+			totalIndexes += len(table.Indexes)
+		}
+	}
+
+	fmt.Fprintf(os.Stderr, "      Schemas: %d, Tables: %d, Columns: %d, Constraints: %d, Indexes: %d\n",
+		len(db.Schemas), totalTables, totalColumns, totalConstraints, totalIndexes)
+}
+
+func parseSkipTables(skipTablesStr string) map[string]bool {
+	skipTables := make(map[string]bool)
+	if skipTablesStr == "" {
+		return skipTables
+	}
+
+	// Split by comma and trim whitespace
+	parts := strings.Split(skipTablesStr, ",")
+	for _, part := range parts {
+		trimmed := strings.TrimSpace(part)
+		if trimmed != "" {
+			// Store in lowercase for case-insensitive matching
+			skipTables[strings.ToLower(trimmed)] = true
+		}
+	}
+
+	return skipTables
+}

cmd/relspec/root.go

@@ -22,4 +22,6 @@ func init() {
 	rootCmd.AddCommand(scriptsCmd)
 	rootCmd.AddCommand(templCmd)
 	rootCmd.AddCommand(editCmd)
+	rootCmd.AddCommand(mergeCmd)
+	rootCmd.AddCommand(splitCmd)
 }

cmd/relspec/split.go

@@ -0,0 +1,318 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"git.warky.dev/wdevs/relspecgo/pkg/models"
+)
+
+var (
+	splitSourceType    string
+	splitSourcePath    string
+	splitSourceConn    string
+	splitTargetType    string
+	splitTargetPath    string
+	splitSchemas       string
+	splitTables        string
+	splitPackageName   string
+	splitDatabaseName  string
+	splitExcludeSchema string
+	splitExcludeTables string
+)
+
+var splitCmd = &cobra.Command{
+	Use:   "split",
+	Short: "Split database schemas to extract selected tables into a separate database",
+	Long: `Extract selected schemas and tables from a database and write them to a separate output.
+
+The split command allows you to:
+- Select specific schemas to include in the output
+- Select specific tables within schemas
+- Exclude specific schemas or tables if preferred
+- Export the selected subset to any supported format
+
+Input formats:
+  - dbml: DBML schema files
+  - dctx: DCTX schema files
+  - drawdb: DrawDB JSON files
+  - graphql: GraphQL schema files (.graphql, SDL)
+  - json: JSON database schema
+  - yaml: YAML database schema
+  - gorm: GORM model files (Go, file or directory)
+  - bun: Bun model files (Go, file or directory)
+  - drizzle: Drizzle ORM schema files (TypeScript, file or directory)
+  - prisma: Prisma schema files (.prisma)
+  - typeorm: TypeORM entity files (TypeScript)
+  - pgsql: PostgreSQL database (live connection)
+
+Output formats:
+  - dbml: DBML schema files
+  - dctx: DCTX schema files
+  - drawdb: DrawDB JSON files
+  - graphql: GraphQL schema files (.graphql, SDL)
+  - json: JSON database schema
+  - yaml: YAML database schema
+  - gorm: GORM model files (Go)
+  - bun: Bun model files (Go)
+  - drizzle: Drizzle ORM schema files (TypeScript)
+  - prisma: Prisma schema files (.prisma)
+  - typeorm: TypeORM entity files (TypeScript)
+  - pgsql: PostgreSQL SQL schema
+
+Examples:
+  # Split specific schemas from DBML
+  relspec split --from dbml --from-path schema.dbml \
+                --schemas public,auth \
+                --to json --to-path subset.json
+
+  # Extract specific tables from PostgreSQL
+  relspec split --from pgsql \
+                --from-conn "postgres://user:pass@localhost:5432/mydb" \
+                --schemas public \
+                --tables users,orders,products \
+                --to dbml --to-path subset.dbml
+
+  # Exclude specific tables
+  relspec split --from json --from-path schema.json \
+                --exclude-tables "audit_log,system_config,temp_data" \
+                --to json --to-path public_schema.json
+
+  # Split and convert to GORM
+  relspec split --from json --from-path schema.json \
+                --tables "users,posts,comments" \
+                --to gorm --to-path models/ --package models \
+                --database-name MyAppDB
+
+  # Exclude specific schema and tables
+  relspec split --from pgsql \
+                --from-conn "postgres://user:pass@localhost/db" \
+                --exclude-schema pg_catalog,information_schema \
+                --exclude-tables "temp_users,debug_logs" \
+                --to json --to-path public_schema.json`,
+	RunE: runSplit,
+}
+
+func init() {
+	splitCmd.Flags().StringVar(&splitSourceType, "from", "", "Source format (dbml, dctx, drawdb, graphql, json, yaml, gorm, bun, drizzle, prisma, typeorm, pgsql)")
+	splitCmd.Flags().StringVar(&splitSourcePath, "from-path", "", "Source file path (for file-based formats)")
+	splitCmd.Flags().StringVar(&splitSourceConn, "from-conn", "", "Source connection string (for database formats)")
+
+	splitCmd.Flags().StringVar(&splitTargetType, "to", "", "Target format (dbml, dctx, drawdb, graphql, json, yaml, gorm, bun, drizzle, prisma, typeorm, pgsql)")
+	splitCmd.Flags().StringVar(&splitTargetPath, "to-path", "", "Target output path (file or directory)")
+	splitCmd.Flags().StringVar(&splitPackageName, "package", "", "Package name (for code generation formats like gorm/bun)")
+	splitCmd.Flags().StringVar(&splitDatabaseName, "database-name", "", "Override database name in output")
+
+	splitCmd.Flags().StringVar(&splitSchemas, "schemas", "", "Comma-separated list of schema names to include")
+	splitCmd.Flags().StringVar(&splitTables, "tables", "", "Comma-separated list of table names to include (case-insensitive)")
+	splitCmd.Flags().StringVar(&splitExcludeSchema, "exclude-schema", "", "Comma-separated list of schema names to exclude")
+	splitCmd.Flags().StringVar(&splitExcludeTables, "exclude-tables", "", "Comma-separated list of table names to exclude (case-insensitive)")
+
+	err := splitCmd.MarkFlagRequired("from")
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error marking from flag as required: %v\n", err)
+	}
+	err = splitCmd.MarkFlagRequired("to")
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error marking to flag as required: %v\n", err)
+	}
+	err = splitCmd.MarkFlagRequired("to-path")
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error marking to-path flag as required: %v\n", err)
+	}
+}
+
+func runSplit(cmd *cobra.Command, args []string) error {
+	fmt.Fprintf(os.Stderr, "\n=== RelSpec Schema Split ===\n")
+	fmt.Fprintf(os.Stderr, "Started at: %s\n\n", getCurrentTimestamp())
+
+	// Read source database
+	fmt.Fprintf(os.Stderr, "[1/3] Reading source schema...\n")
+	fmt.Fprintf(os.Stderr, "      Format: %s\n", splitSourceType)
+	if splitSourcePath != "" {
+		fmt.Fprintf(os.Stderr, "      Path:   %s\n", splitSourcePath)
+	}
+	if splitSourceConn != "" {
+		fmt.Fprintf(os.Stderr, "      Conn:   %s\n", maskPassword(splitSourceConn))
+	}
+
+	db, err := readDatabaseForConvert(splitSourceType, splitSourcePath, splitSourceConn)
+	if err != nil {
+		return fmt.Errorf("failed to read source: %w", err)
+	}
+
+	fmt.Fprintf(os.Stderr, "      ✓ Successfully read database '%s'\n", db.Name)
+	fmt.Fprintf(os.Stderr, "      Found: %d schema(s)\n", len(db.Schemas))
+
+	totalTables := 0
+	for _, schema := range db.Schemas {
+		totalTables += len(schema.Tables)
+	}
+	fmt.Fprintf(os.Stderr, "      Found: %d table(s)\n\n", totalTables)
+
+	// Filter the database
+	fmt.Fprintf(os.Stderr, "[2/3] Filtering schemas and tables...\n")
+	filteredDB, err := filterDatabase(db)
+	if err != nil {
+		return fmt.Errorf("failed to filter database: %w", err)
+	}
+
+	if splitDatabaseName != "" {
+		filteredDB.Name = splitDatabaseName
+	}
+
+	filteredTables := 0
+	for _, schema := range filteredDB.Schemas {
+		filteredTables += len(schema.Tables)
+	}
+	fmt.Fprintf(os.Stderr, "      ✓ Filtered to: %d schema(s), %d table(s)\n\n", len(filteredDB.Schemas), filteredTables)
+
+	// Write to target format
+	fmt.Fprintf(os.Stderr, "[3/3] Writing to target format...\n")
+	fmt.Fprintf(os.Stderr, "      Format: %s\n", splitTargetType)
+	fmt.Fprintf(os.Stderr, "      Output: %s\n", splitTargetPath)
+	if splitPackageName != "" {
+		fmt.Fprintf(os.Stderr, "      Package: %s\n", splitPackageName)
+	}
+
+	err = writeDatabase(
+		filteredDB,
+		splitTargetType,
+		splitTargetPath,
+		splitPackageName,
+		"", // no schema filter for split
+	)
+	if err != nil {
+		return fmt.Errorf("failed to write output: %w", err)
+	}
+
+	fmt.Fprintf(os.Stderr, "      ✓ Successfully written to '%s'\n\n", splitTargetPath)
+	fmt.Fprintf(os.Stderr, "=== Split Completed Successfully ===\n")
+	fmt.Fprintf(os.Stderr, "Completed at: %s\n\n", getCurrentTimestamp())
+
+	return nil
+}
+
+// filterDatabase filters the database based on provided criteria
+func filterDatabase(db *models.Database) (*models.Database, error) {
+	filteredDB := &models.Database{
+		Name:            db.Name,
+		Description:     db.Description,
+		Comment:         db.Comment,
+		DatabaseType:    db.DatabaseType,
+		DatabaseVersion: db.DatabaseVersion,
+		SourceFormat:    db.SourceFormat,
+		UpdatedAt:       db.UpdatedAt,
+		GUID:            db.GUID,
+		Schemas:         []*models.Schema{},
+		Domains:         db.Domains, // Keep domains for now
+	}
+
+	// Parse filter flags
+	includeSchemas := parseCommaSeparated(splitSchemas)
+	includeTables := parseCommaSeparated(splitTables)
+	excludeSchemas := parseCommaSeparated(splitExcludeSchema)
+	excludeTables := parseCommaSeparated(splitExcludeTables)
+
+	// Convert table names to lowercase for case-insensitive matching
+	includeTablesLower := make(map[string]bool)
+	for _, t := range includeTables {
+		includeTablesLower[strings.ToLower(t)] = true
+	}
+
+	excludeTablesLower := make(map[string]bool)
+	for _, t := range excludeTables {
+		excludeTablesLower[strings.ToLower(t)] = true
+	}
+
+	// Iterate through schemas
+	for _, schema := range db.Schemas {
+		// Check if schema should be excluded
+		if contains(excludeSchemas, schema.Name) {
+			continue
+		}
+
+		// Check if schema should be included
+		if len(includeSchemas) > 0 && !contains(includeSchemas, schema.Name) {
+			continue
+		}
+
+		// Create a copy of the schema with filtered tables
+		filteredSchema := &models.Schema{
+			Name:        schema.Name,
+			Description: schema.Description,
+			Owner:       schema.Owner,
+			Permissions: schema.Permissions,
+			Comment:     schema.Comment,
+			Metadata:    schema.Metadata,
+			Scripts:     schema.Scripts,
+			Sequence:    schema.Sequence,
+			Relations:   schema.Relations,
+			Enums:       schema.Enums,
+			UpdatedAt:   schema.UpdatedAt,
+			GUID:        schema.GUID,
+			Tables:      []*models.Table{},
+			Views:       schema.Views,
+			Sequences:   schema.Sequences,
+		}
+
+		// Filter tables within the schema
+		for _, table := range schema.Tables {
+			tableLower := strings.ToLower(table.Name)
+
+			// Check if table should be excluded
+			if excludeTablesLower[tableLower] {
+				continue
+			}
+
+			// If specific tables are requested, only include those
+			if len(includeTablesLower) > 0 {
+				if !includeTablesLower[tableLower] {
+					continue
+				}
+			}
+			filteredSchema.Tables = append(filteredSchema.Tables, table)
+		}
+
+		// Only add schema if it has tables (unless no table filter was specified)
+		if len(filteredSchema.Tables) > 0 || (len(includeTablesLower) == 0 && len(excludeTablesLower) == 0) {
+			filteredDB.Schemas = append(filteredDB.Schemas, filteredSchema)
+		}
+	}
+
+	if len(filteredDB.Schemas) == 0 {
+		return nil, fmt.Errorf("no schemas matched the filter criteria")
+	}
+
+	return filteredDB, nil
+}
+
+// parseCommaSeparated parses a comma-separated string into a slice, trimming whitespace
+func parseCommaSeparated(s string) []string {
+	if s == "" {
+		return []string{}
+	}
+
+	parts := strings.Split(s, ",")
+	result := make([]string, 0, len(parts))
+	for _, p := range parts {
+		trimmed := strings.TrimSpace(p)
+		if trimmed != "" {
+			result = append(result, trimmed)
+		}
+	}
+	return result
+}
+
+// contains checks if a string is in a slice
+func contains(slice []string, item string) bool {
+	for _, s := range slice {
+		if s == item {
+			return true
+		}
+	}
+	return false
+}

pkg/merge/merge.go

@@ -0,0 +1,574 @@
+// Package merge provides utilities for merging database schemas.
+// It allows combining schemas from multiple sources while avoiding duplicates,
+// supporting only additive operations (no deletion or modification of existing items).
+package merge
+
+import (
+	"fmt"
+	"strings"
+
+	"git.warky.dev/wdevs/relspecgo/pkg/models"
+)
+
+// MergeResult represents the result of a merge operation
+type MergeResult struct {
+	SchemasAdded   int
+	TablesAdded    int
+	ColumnsAdded   int
+	RelationsAdded int
+	DomainsAdded   int
+	EnumsAdded     int
+	ViewsAdded     int
+	SequencesAdded int
+}
+
+// MergeOptions contains options for merge operations
+type MergeOptions struct {
+	SkipDomains    bool
+	SkipRelations  bool
+	SkipEnums      bool
+	SkipViews      bool
+	SkipSequences  bool
+	SkipTableNames map[string]bool // Tables to skip during merge (keyed by table name)
+}
+
+// MergeDatabases merges the source database into the target database.
+// Only adds missing items; existing items are not modified.
+func MergeDatabases(target, source *models.Database, opts *MergeOptions) *MergeResult {
+	if opts == nil {
+		opts = &MergeOptions{}
+	}
+
+	result := &MergeResult{}
+
+	if target == nil || source == nil {
+		return result
+	}
+
+	// Merge schemas and their contents
+	result.merge(target, source, opts)
+
+	return result
+}
+
+func (r *MergeResult) merge(target, source *models.Database, opts *MergeOptions) {
+	// Create maps of existing schemas for quick lookup
+	existingSchemas := make(map[string]*models.Schema)
+	for _, schema := range target.Schemas {
+		existingSchemas[schema.SQLName()] = schema
+	}
+
+	// Merge schemas
+	for _, srcSchema := range source.Schemas {
+		schemaName := srcSchema.SQLName()
+		if tgtSchema, exists := existingSchemas[schemaName]; exists {
+			// Schema exists, merge its contents
+			r.mergeSchemaContents(tgtSchema, srcSchema, opts)
+		} else {
+			// Schema doesn't exist, add it
+			newSchema := cloneSchema(srcSchema)
+			target.Schemas = append(target.Schemas, newSchema)
+			r.SchemasAdded++
+		}
+	}
+
+	// Merge domains if not skipped
+	if !opts.SkipDomains {
+		r.mergeDomains(target, source)
+	}
+}
+
+func (r *MergeResult) mergeSchemaContents(target, source *models.Schema, opts *MergeOptions) {
+	// Merge tables
+	r.mergeTables(target, source, opts)
+
+	// Merge views if not skipped
+	if !opts.SkipViews {
+		r.mergeViews(target, source)
+	}
+
+	// Merge sequences if not skipped
+	if !opts.SkipSequences {
+		r.mergeSequences(target, source)
+	}
+
+	// Merge enums if not skipped
+	if !opts.SkipEnums {
+		r.mergeEnums(target, source)
+	}
+
+	// Merge relations if not skipped
+	if !opts.SkipRelations {
+		r.mergeRelations(target, source)
+	}
+}
+
+func (r *MergeResult) mergeTables(schema *models.Schema, source *models.Schema, opts *MergeOptions) {
+	// Create map of existing tables
+	existingTables := make(map[string]*models.Table)
+	for _, table := range schema.Tables {
+		existingTables[table.SQLName()] = table
+	}
+
+	// Merge tables
+	for _, srcTable := range source.Tables {
+		tableName := srcTable.SQLName()
+
+		// Skip if table is in the skip list (case-insensitive)
+		if opts != nil && opts.SkipTableNames != nil && opts.SkipTableNames[strings.ToLower(tableName)] {
+			continue
+		}
+
+		if tgtTable, exists := existingTables[tableName]; exists {
+			// Table exists, merge its columns
+			r.mergeColumns(tgtTable, srcTable)
+		} else {
+			// Table doesn't exist, add it
+			newTable := cloneTable(srcTable)
+			schema.Tables = append(schema.Tables, newTable)
+			r.TablesAdded++
+			// Count columns in the newly added table
+			r.ColumnsAdded += len(newTable.Columns)
+		}
+	}
+}
+
+func (r *MergeResult) mergeColumns(table *models.Table, srcTable *models.Table) {
+	// Create map of existing columns
+	existingColumns := make(map[string]*models.Column)
+	for colName := range table.Columns {
+		existingColumns[colName] = table.Columns[colName]
+	}
+
+	// Merge columns
+	for colName, srcCol := range srcTable.Columns {
+		if _, exists := existingColumns[colName]; !exists {
+			// Column doesn't exist, add it
+			newCol := cloneColumn(srcCol)
+			table.Columns[colName] = newCol
+			r.ColumnsAdded++
+		}
+	}
+}
+
+func (r *MergeResult) mergeViews(schema *models.Schema, source *models.Schema) {
+	// Create map of existing views
+	existingViews := make(map[string]*models.View)
+	for _, view := range schema.Views {
+		existingViews[view.SQLName()] = view
+	}
+
+	// Merge views
+	for _, srcView := range source.Views {
+		viewName := srcView.SQLName()
+		if _, exists := existingViews[viewName]; !exists {
+			// View doesn't exist, add it
+			newView := cloneView(srcView)
+			schema.Views = append(schema.Views, newView)
+			r.ViewsAdded++
+		}
+	}
+}
+
+func (r *MergeResult) mergeSequences(schema *models.Schema, source *models.Schema) {
+	// Create map of existing sequences
+	existingSequences := make(map[string]*models.Sequence)
+	for _, seq := range schema.Sequences {
+		existingSequences[seq.SQLName()] = seq
+	}
+
+	// Merge sequences
+	for _, srcSeq := range source.Sequences {
+		seqName := srcSeq.SQLName()
+		if _, exists := existingSequences[seqName]; !exists {
+			// Sequence doesn't exist, add it
+			newSeq := cloneSequence(srcSeq)
+			schema.Sequences = append(schema.Sequences, newSeq)
+			r.SequencesAdded++
+		}
+	}
+}
+
+func (r *MergeResult) mergeEnums(schema *models.Schema, source *models.Schema) {
+	// Create map of existing enums
+	existingEnums := make(map[string]*models.Enum)
+	for _, enum := range schema.Enums {
+		existingEnums[enum.SQLName()] = enum
+	}
+
+	// Merge enums
+	for _, srcEnum := range source.Enums {
+		enumName := srcEnum.SQLName()
+		if _, exists := existingEnums[enumName]; !exists {
+			// Enum doesn't exist, add it
+			newEnum := cloneEnum(srcEnum)
+			schema.Enums = append(schema.Enums, newEnum)
+			r.EnumsAdded++
+		}
+	}
+}
+
+func (r *MergeResult) mergeRelations(schema *models.Schema, source *models.Schema) {
+	// Create map of existing relations
+	existingRelations := make(map[string]*models.Relationship)
+	for _, rel := range schema.Relations {
+		existingRelations[rel.SQLName()] = rel
+	}
+
+	// Merge relations
+	for _, srcRel := range source.Relations {
+		if _, exists := existingRelations[srcRel.SQLName()]; !exists {
+			// Relation doesn't exist, add it
+			newRel := cloneRelation(srcRel)
+			schema.Relations = append(schema.Relations, newRel)
+			r.RelationsAdded++
+		}
+	}
+}
+
+func (r *MergeResult) mergeDomains(target *models.Database, source *models.Database) {
+	// Create map of existing domains
+	existingDomains := make(map[string]*models.Domain)
+	for _, domain := range target.Domains {
+		existingDomains[domain.SQLName()] = domain
+	}
+
+	// Merge domains
+	for _, srcDomain := range source.Domains {
+		domainName := srcDomain.SQLName()
+		if _, exists := existingDomains[domainName]; !exists {
+			// Domain doesn't exist, add it
+			newDomain := cloneDomain(srcDomain)
+			target.Domains = append(target.Domains, newDomain)
+			r.DomainsAdded++
+		}
+	}
+}
+
+// Clone functions to create deep copies of models
+
+func cloneSchema(schema *models.Schema) *models.Schema {
+	if schema == nil {
+		return nil
+	}
+	newSchema := &models.Schema{
+		Name:        schema.Name,
+		Description: schema.Description,
+		Owner:       schema.Owner,
+		Comment:     schema.Comment,
+		Sequence:    schema.Sequence,
+		UpdatedAt:   schema.UpdatedAt,
+		Tables:      make([]*models.Table, 0),
+		Views:       make([]*models.View, 0),
+		Sequences:   make([]*models.Sequence, 0),
+		Enums:       make([]*models.Enum, 0),
+		Relations:   make([]*models.Relationship, 0),
+	}
+
+	if schema.Permissions != nil {
+		newSchema.Permissions = make(map[string]string)
+		for k, v := range schema.Permissions {
+			newSchema.Permissions[k] = v
+		}
+	}
+
+	if schema.Metadata != nil {
+		newSchema.Metadata = make(map[string]interface{})
+		for k, v := range schema.Metadata {
+			newSchema.Metadata[k] = v
+		}
+	}
+
+	if schema.Scripts != nil {
+		newSchema.Scripts = make([]*models.Script, len(schema.Scripts))
+		copy(newSchema.Scripts, schema.Scripts)
+	}
+
+	// Clone tables
+	for _, table := range schema.Tables {
+		newSchema.Tables = append(newSchema.Tables, cloneTable(table))
+	}
+
+	// Clone views
+	for _, view := range schema.Views {
+		newSchema.Views = append(newSchema.Views, cloneView(view))
+	}
+
+	// Clone sequences
+	for _, seq := range schema.Sequences {
+		newSchema.Sequences = append(newSchema.Sequences, cloneSequence(seq))
+	}
+
+	// Clone enums
+	for _, enum := range schema.Enums {
+		newSchema.Enums = append(newSchema.Enums, cloneEnum(enum))
+	}
+
+	// Clone relations
+	for _, rel := range schema.Relations {
+		newSchema.Relations = append(newSchema.Relations, cloneRelation(rel))
+	}
+
+	return newSchema
+}
+
+func cloneTable(table *models.Table) *models.Table {
+	if table == nil {
+		return nil
+	}
+	newTable := &models.Table{
+		Name:        table.Name,
+		Description: table.Description,
+		Schema:      table.Schema,
+		Comment:     table.Comment,
+		Sequence:    table.Sequence,
+		UpdatedAt:   table.UpdatedAt,
+		Columns:     make(map[string]*models.Column),
+		Constraints: make(map[string]*models.Constraint),
+		Indexes:     make(map[string]*models.Index),
+	}
+
+	if table.Metadata != nil {
+		newTable.Metadata = make(map[string]interface{})
+		for k, v := range table.Metadata {
+			newTable.Metadata[k] = v
+		}
+	}
+
+	// Clone columns
+	for colName, col := range table.Columns {
+		newTable.Columns[colName] = cloneColumn(col)
+	}
+
+	// Clone constraints
+	for constName, constraint := range table.Constraints {
+		newTable.Constraints[constName] = cloneConstraint(constraint)
+	}
+
+	// Clone indexes
+	for idxName, index := range table.Indexes {
+		newTable.Indexes[idxName] = cloneIndex(index)
+	}
+
+	return newTable
+}
+
+func cloneColumn(col *models.Column) *models.Column {
+	if col == nil {
+		return nil
+	}
+	newCol := &models.Column{
+		Name:          col.Name,
+		Type:          col.Type,
+		Description:   col.Description,
+		Comment:       col.Comment,
+		IsPrimaryKey:  col.IsPrimaryKey,
+		NotNull:       col.NotNull,
+		Default:       col.Default,
+		Precision:     col.Precision,
+		Scale:         col.Scale,
+		Length:        col.Length,
+		Sequence:      col.Sequence,
+		AutoIncrement: col.AutoIncrement,
+		Collation:     col.Collation,
+	}
+
+	return newCol
+}
+
+func cloneConstraint(constraint *models.Constraint) *models.Constraint {
+	if constraint == nil {
+		return nil
+	}
+	newConstraint := &models.Constraint{
+		Type:              constraint.Type,
+		Columns:           make([]string, len(constraint.Columns)),
+		ReferencedTable:   constraint.ReferencedTable,
+		ReferencedSchema:  constraint.ReferencedSchema,
+		ReferencedColumns: make([]string, len(constraint.ReferencedColumns)),
+		OnUpdate:          constraint.OnUpdate,
+		OnDelete:          constraint.OnDelete,
+		Expression:        constraint.Expression,
+		Name:              constraint.Name,
+		Deferrable:        constraint.Deferrable,
+		InitiallyDeferred: constraint.InitiallyDeferred,
+		Sequence:          constraint.Sequence,
+	}
+	copy(newConstraint.Columns, constraint.Columns)
+	copy(newConstraint.ReferencedColumns, constraint.ReferencedColumns)
+	return newConstraint
+}
+
+func cloneIndex(index *models.Index) *models.Index {
+	if index == nil {
+		return nil
+	}
+	newIndex := &models.Index{
+		Name:        index.Name,
+		Description: index.Description,
+		Table:       index.Table,
+		Schema:      index.Schema,
+		Columns:     make([]string, len(index.Columns)),
+		Unique:      index.Unique,
+		Type:        index.Type,
+		Where:       index.Where,
+		Concurrent:  index.Concurrent,
+		Include:     make([]string, len(index.Include)),
+		Comment:     index.Comment,
+		Sequence:    index.Sequence,
+	}
+	copy(newIndex.Columns, index.Columns)
+	copy(newIndex.Include, index.Include)
+	return newIndex
+}
+
+func cloneView(view *models.View) *models.View {
+	if view == nil {
+		return nil
+	}
+	newView := &models.View{
+		Name:        view.Name,
+		Description: view.Description,
+		Schema:      view.Schema,
+		Definition:  view.Definition,
+		Comment:     view.Comment,
+		Sequence:    view.Sequence,
+		Columns:     make(map[string]*models.Column),
+	}
+
+	if view.Metadata != nil {
+		newView.Metadata = make(map[string]interface{})
+		for k, v := range view.Metadata {
+			newView.Metadata[k] = v
+		}
+	}
+
+	// Clone columns
+	for colName, col := range view.Columns {
+		newView.Columns[colName] = cloneColumn(col)
+	}
+
+	return newView
+}
+
+func cloneSequence(seq *models.Sequence) *models.Sequence {
+	if seq == nil {
+		return nil
+	}
+	newSeq := &models.Sequence{
+		Name:          seq.Name,
+		Description:   seq.Description,
+		Schema:        seq.Schema,
+		StartValue:    seq.StartValue,
+		MinValue:      seq.MinValue,
+		MaxValue:      seq.MaxValue,
+		IncrementBy:   seq.IncrementBy,
+		CacheSize:     seq.CacheSize,
+		Cycle:         seq.Cycle,
+		OwnedByTable:  seq.OwnedByTable,
+		OwnedByColumn: seq.OwnedByColumn,
+		Comment:       seq.Comment,
+		Sequence:      seq.Sequence,
+	}
+	return newSeq
+}
+
+func cloneEnum(enum *models.Enum) *models.Enum {
+	if enum == nil {
+		return nil
+	}
+	newEnum := &models.Enum{
+		Name:   enum.Name,
+		Values: make([]string, len(enum.Values)),
+		Schema: enum.Schema,
+	}
+	copy(newEnum.Values, enum.Values)
+	return newEnum
+}
+
+func cloneRelation(rel *models.Relationship) *models.Relationship {
+	if rel == nil {
+		return nil
+	}
+	newRel := &models.Relationship{
+		Name:          rel.Name,
+		Type:          rel.Type,
+		FromTable:     rel.FromTable,
+		FromSchema:    rel.FromSchema,
+		FromColumns:   make([]string, len(rel.FromColumns)),
+		ToTable:       rel.ToTable,
+		ToSchema:      rel.ToSchema,
+		ToColumns:     make([]string, len(rel.ToColumns)),
+		ForeignKey:    rel.ForeignKey,
+		ThroughTable:  rel.ThroughTable,
+		ThroughSchema: rel.ThroughSchema,
+		Description:   rel.Description,
+		Sequence:      rel.Sequence,
+	}
+
+	if rel.Properties != nil {
+		newRel.Properties = make(map[string]string)
+		for k, v := range rel.Properties {
+			newRel.Properties[k] = v
+		}
+	}
+
+	copy(newRel.FromColumns, rel.FromColumns)
+	copy(newRel.ToColumns, rel.ToColumns)
+	return newRel
+}
+
+func cloneDomain(domain *models.Domain) *models.Domain {
+	if domain == nil {
+		return nil
+	}
+	newDomain := &models.Domain{
+		Name:        domain.Name,
+		Description: domain.Description,
+		Comment:     domain.Comment,
+		Sequence:    domain.Sequence,
+		Tables:      make([]*models.DomainTable, len(domain.Tables)),
+	}
+
+	if domain.Metadata != nil {
+		newDomain.Metadata = make(map[string]interface{})
+		for k, v := range domain.Metadata {
+			newDomain.Metadata[k] = v
+		}
+	}
+
+	copy(newDomain.Tables, domain.Tables)
+	return newDomain
+}
+
+// GetMergeSummary returns a human-readable summary of the merge result
+func GetMergeSummary(result *MergeResult) string {
+	if result == nil {
+		return "No merge result available"
+	}
+
+	lines := []string{
+		"=== Merge Summary ===",
+		fmt.Sprintf("Schemas added:     %d", result.SchemasAdded),
+		fmt.Sprintf("Tables added:      %d", result.TablesAdded),
+		fmt.Sprintf("Columns added:     %d", result.ColumnsAdded),
+		fmt.Sprintf("Views added:       %d", result.ViewsAdded),
+		fmt.Sprintf("Sequences added:   %d", result.SequencesAdded),
+		fmt.Sprintf("Enums added:       %d", result.EnumsAdded),
+		fmt.Sprintf("Relations added:   %d", result.RelationsAdded),
+		fmt.Sprintf("Domains added:     %d", result.DomainsAdded),
+	}
+
+	totalAdded := result.SchemasAdded + result.TablesAdded + result.ColumnsAdded +
+		result.ViewsAdded + result.SequencesAdded + result.EnumsAdded +
+		result.RelationsAdded + result.DomainsAdded
+
+	lines = append(lines, fmt.Sprintf("Total items added: %d", totalAdded))
+
+	summary := ""
+	for _, line := range lines {
+		summary += line + "\n"
+	}
+
+	return summary
+}

pkg/models/models.go

@@ -7,6 +7,8 @@ package models
 import (
 	"strings"
 	"time"
+
+	"github.com/google/uuid"
 )
 
 // DatabaseType represents the type of database system.
@@ -30,6 +32,7 @@ type Database struct {
 	DatabaseVersion string       `json:"database_version,omitempty" yaml:"database_version,omitempty" xml:"database_version,omitempty"`
 	SourceFormat    string       `json:"source_format,omitempty" yaml:"source_format,omitempty" xml:"source_format,omitempty"` // Source Format of the database.
 	UpdatedAt       string       `json:"updatedat,omitempty" yaml:"updatedat,omitempty" xml:"updatedat,omitempty"`
+	GUID            string       `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // SQLName returns the database name in lowercase for SQL compatibility.
@@ -51,6 +54,7 @@ type Domain struct {
 	Comment     string         `json:"comment,omitempty" yaml:"comment,omitempty" xml:"comment,omitempty"`
 	Metadata    map[string]any `json:"metadata,omitempty" yaml:"metadata,omitempty" xml:"-"`
 	Sequence    uint           `json:"sequence,omitempty" yaml:"sequence,omitempty" xml:"sequence,omitempty"`
+	GUID        string         `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // SQLName returns the domain name in lowercase for SQL compatibility.
@@ -66,6 +70,7 @@ type DomainTable struct {
 	SchemaName string `json:"schema_name" yaml:"schema_name" xml:"schema_name"`
 	Sequence   uint   `json:"sequence,omitempty" yaml:"sequence,omitempty" xml:"sequence,omitempty"`
 	RefTable   *Table `json:"-" yaml:"-" xml:"-"` // Excluded to prevent circular references
+	GUID       string `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // Schema represents a database schema, which is a logical grouping of database objects
@@ -86,6 +91,7 @@ type Schema struct {
 	Relations   []*Relationship   `json:"relations,omitempty" yaml:"relations,omitempty" xml:"-"`
 	Enums       []*Enum           `json:"enums,omitempty" yaml:"enums,omitempty" xml:"enums"`
 	UpdatedAt   string            `json:"updatedat,omitempty" yaml:"updatedat,omitempty" xml:"updatedat,omitempty"`
+	GUID        string            `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // UpdaUpdateDateted sets the UpdatedAt field to the current time in RFC3339 format.
@@ -117,6 +123,7 @@ type Table struct {
 	Sequence      uint                     `json:"sequence,omitempty" yaml:"sequence,omitempty" xml:"sequence,omitempty"`
 	RefSchema     *Schema                  `json:"-" yaml:"-" xml:"-"` // Excluded to prevent circular references
 	UpdatedAt     string                   `json:"updatedat,omitempty" yaml:"updatedat,omitempty" xml:"updatedat,omitempty"`
+	GUID          string                   `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // UpdateDate sets the UpdatedAt field to the current time in RFC3339 format.
@@ -165,6 +172,7 @@ type View struct {
 	Metadata    map[string]any     `json:"metadata,omitempty" yaml:"metadata,omitempty" xml:"-"`
 	Sequence    uint               `json:"sequence,omitempty" yaml:"sequence,omitempty" xml:"sequence,omitempty"`
 	RefSchema   *Schema            `json:"-" yaml:"-" xml:"-"` // Excluded to prevent circular references
+	GUID        string             `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // SQLName returns the view name in lowercase for SQL compatibility.
@@ -188,6 +196,7 @@ type Sequence struct {
 	Comment       string  `json:"comment,omitempty" yaml:"comment,omitempty" xml:"comment,omitempty"`
 	Sequence      uint    `json:"sequence,omitempty" yaml:"sequence,omitempty" xml:"sequence,omitempty"`
 	RefSchema     *Schema `json:"-" yaml:"-" xml:"-"` // Excluded to prevent circular references
+	GUID          string  `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // SQLName returns the sequence name in lowercase for SQL compatibility.
@@ -212,6 +221,7 @@ type Column struct {
 	Comment       string `json:"comment,omitempty" yaml:"comment,omitempty" xml:"comment,omitempty"`
 	Collation     string `json:"collation,omitempty" yaml:"collation,omitempty" xml:"collation,omitempty"`
 	Sequence      uint   `json:"sequence,omitempty" yaml:"sequence,omitempty" xml:"sequence,omitempty"`
+	GUID          string `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // SQLName returns the column name in lowercase for SQL compatibility.
@@ -234,6 +244,7 @@ type Index struct {
 	Include     []string `json:"include,omitempty" yaml:"include,omitempty" xml:"include,omitempty"` // INCLUDE columns
 	Comment     string   `json:"comment,omitempty" yaml:"comment,omitempty" xml:"comment,omitempty"`
 	Sequence    uint     `json:"sequence,omitempty" yaml:"sequence,omitempty" xml:"sequence,omitempty"`
+	GUID        string   `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // SQLName returns the index name in lowercase for SQL compatibility.
@@ -268,6 +279,7 @@ type Relationship struct {
 	ThroughSchema string            `json:"through_schema,omitempty" yaml:"through_schema,omitempty" xml:"through_schema,omitempty"`
 	Description   string            `json:"description,omitempty" yaml:"description,omitempty" xml:"description,omitempty"`
 	Sequence      uint              `json:"sequence,omitempty" yaml:"sequence,omitempty" xml:"sequence,omitempty"`
+	GUID          string            `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // SQLName returns the relationship name in lowercase for SQL compatibility.
@@ -292,6 +304,7 @@ type Constraint struct {
 	Deferrable        bool           `json:"deferrable,omitempty" yaml:"deferrable,omitempty" xml:"deferrable,omitempty"`
 	InitiallyDeferred bool           `json:"initially_deferred,omitempty" yaml:"initially_deferred,omitempty" xml:"initially_deferred,omitempty"`
 	Sequence          uint           `json:"sequence,omitempty" yaml:"sequence,omitempty" xml:"sequence,omitempty"`
+	GUID              string         `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // SQLName returns the constraint name in lowercase for SQL compatibility.
@@ -307,6 +320,7 @@ type Enum struct {
 	Name   string   `json:"name" yaml:"name" xml:"name"`
 	Values []string `json:"values" yaml:"values" xml:"values"`
 	Schema string   `json:"schema,omitempty" yaml:"schema,omitempty" xml:"schema,omitempty"`
+	GUID   string   `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // SQLName returns the enum name in lowercase for SQL compatibility.
@@ -314,6 +328,16 @@ func (d *Enum) SQLName() string {
 	return strings.ToLower(d.Name)
 }
 
+// InitEnum initializes a new Enum with empty values slice
+func InitEnum(name, schema string) *Enum {
+	return &Enum{
+		Name:   name,
+		Schema: schema,
+		Values: make([]string, 0),
+		GUID:   uuid.New().String(),
+	}
+}
+
 // Supported constraint types.
 const (
 	PrimaryKeyConstraint ConstraintType = "primary_key" // Primary key uniquely identifies each record
@@ -335,6 +359,7 @@ type Script struct {
 	Version     string   `json:"version,omitempty" yaml:"version,omitempty" xml:"version,omitempty"`
 	Priority    int      `json:"priority,omitempty" yaml:"priority,omitempty" xml:"priority,omitempty"`
 	Sequence    uint     `json:"sequence,omitempty" yaml:"sequence,omitempty" xml:"sequence,omitempty"`
+	GUID        string   `json:"guid" yaml:"guid" xml:"guid"`
 }
 
 // SQLName returns the script name in lowercase for SQL compatibility.
@@ -350,6 +375,7 @@ func InitDatabase(name string) *Database {
 		Name:    name,
 		Schemas: make([]*Schema, 0),
 		Domains: make([]*Domain, 0),
+		GUID:    uuid.New().String(),
 	}
 }
 
@@ -363,6 +389,7 @@ func InitSchema(name string) *Schema {
 		Permissions: make(map[string]string),
 		Metadata:    make(map[string]any),
 		Scripts:     make([]*Script, 0),
+		GUID:        uuid.New().String(),
 	}
 }
 
@@ -376,6 +403,7 @@ func InitTable(name, schema string) *Table {
 		Indexes:       make(map[string]*Index),
 		Relationships: make(map[string]*Relationship),
 		Metadata:      make(map[string]any),
+		GUID:          uuid.New().String(),
 	}
 }
 
@@ -385,6 +413,7 @@ func InitColumn(name, table, schema string) *Column {
 		Name:   name,
 		Table:  table,
 		Schema: schema,
+		GUID:   uuid.New().String(),
 	}
 }
 
@@ -396,6 +425,7 @@ func InitIndex(name, table, schema string) *Index {
 		Schema:  schema,
 		Columns: make([]string, 0),
 		Include: make([]string, 0),
+		GUID:    uuid.New().String(),
 	}
 }
 
@@ -408,6 +438,7 @@ func InitRelation(name, schema string) *Relationship {
 		Properties:  make(map[string]string),
 		FromColumns: make([]string, 0),
 		ToColumns:   make([]string, 0),
+		GUID:        uuid.New().String(),
 	}
 }
 
@@ -417,6 +448,7 @@ func InitRelationship(name string, relType RelationType) *Relationship {
 		Name:       name,
 		Type:       relType,
 		Properties: make(map[string]string),
+		GUID:       uuid.New().String(),
 	}
 }
 
@@ -427,6 +459,7 @@ func InitConstraint(name string, constraintType ConstraintType) *Constraint {
 		Type:              constraintType,
 		Columns:           make([]string, 0),
 		ReferencedColumns: make([]string, 0),
+		GUID:              uuid.New().String(),
 	}
 }
 
@@ -435,6 +468,7 @@ func InitScript(name string) *Script {
 	return &Script{
 		Name:     name,
 		RunAfter: make([]string, 0),
+		GUID:     uuid.New().String(),
 	}
 }
 
@@ -445,6 +479,7 @@ func InitView(name, schema string) *View {
 		Schema:   schema,
 		Columns:  make(map[string]*Column),
 		Metadata: make(map[string]any),
+		GUID:     uuid.New().String(),
 	}
 }
 
@@ -455,6 +490,7 @@ func InitSequence(name, schema string) *Sequence {
 		Schema:      schema,
 		IncrementBy: 1,
 		StartValue:  1,
+		GUID:        uuid.New().String(),
 	}
 }
 
@@ -464,6 +500,7 @@ func InitDomain(name string) *Domain {
 		Name:     name,
 		Tables:   make([]*DomainTable, 0),
 		Metadata: make(map[string]any),
+		GUID:     uuid.New().String(),
 	}
 }
 
@@ -472,5 +509,6 @@ func InitDomainTable(tableName, schemaName string) *DomainTable {
 	return &DomainTable{
 		TableName:  tableName,
 		SchemaName: schemaName,
+		GUID:       uuid.New().String(),
 	}
 }

pkg/readers/bun/reader.go

@@ -632,6 +632,9 @@ func (r *Reader) parseColumn(fieldName string, fieldType ast.Expr, tag string, s
 		column.Name = parts[0]
 	}
 
+	// Track if we found explicit nullability markers
+	hasExplicitNullableMarker := false
+
 	// Parse tag attributes
 	for _, part := range parts[1:] {
 		kv := strings.SplitN(part, ":", 2)
@@ -649,6 +652,10 @@ func (r *Reader) parseColumn(fieldName string, fieldType ast.Expr, tag string, s
 			column.IsPrimaryKey = true
 		case "notnull":
 			column.NotNull = true
+			hasExplicitNullableMarker = true
+		case "nullzero":
+			column.NotNull = false
+			hasExplicitNullableMarker = true
 		case "autoincrement":
 			column.AutoIncrement = true
 		case "default":
@@ -664,17 +671,15 @@ func (r *Reader) parseColumn(fieldName string, fieldType ast.Expr, tag string, s
 
 	// Determine if nullable based on Go type and bun tags
 	// In Bun:
-	// - nullzero tag means the field is nullable (can be NULL in DB)
-	// - absence of nullzero means the field is NOT NULL
-	// - primitive types (int64, bool, string) are NOT NULL by default
-	column.NotNull = true
-	// Primary keys are always NOT NULL
-
-	if strings.Contains(bunTag, "nullzero") {
-		column.NotNull = false
-	} else {
+	// - explicit "notnull" tag means NOT NULL
+	// - explicit "nullzero" tag means nullable
+	// - absence of explicit markers: infer from Go type
+	if !hasExplicitNullableMarker {
+		// Infer from Go type if no explicit marker found
 		column.NotNull = !r.isNullableGoType(fieldType)
 	}
+
+	// Primary keys are always NOT NULL
 	if column.IsPrimaryKey {
 		column.NotNull = true
 	}

pkg/readers/dbml/reader.go

@@ -4,7 +4,9 @@ import (
 	"bufio"
 	"fmt"
 	"os"
+	"path/filepath"
 	"regexp"
+	"sort"
 	"strings"
 
 	"git.warky.dev/wdevs/relspecgo/pkg/models"
@@ -24,11 +26,23 @@ func NewReader(options *readers.ReaderOptions) *Reader {
 }
 
 // ReadDatabase reads and parses DBML input, returning a Database model
+// If FilePath points to a directory, all .dbml files are loaded and merged
 func (r *Reader) ReadDatabase() (*models.Database, error) {
 	if r.options.FilePath == "" {
 		return nil, fmt.Errorf("file path is required for DBML reader")
 	}
 
+	// Check if path is a directory
+	info, err := os.Stat(r.options.FilePath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to stat path: %w", err)
+	}
+
+	if info.IsDir() {
+		return r.readDirectoryDBML(r.options.FilePath)
+	}
+
+	// Single file - existing logic
 	content, err := os.ReadFile(r.options.FilePath)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read file: %w", err)
@@ -67,6 +81,53 @@ func (r *Reader) ReadTable() (*models.Table, error) {
 	return schema.Tables[0], nil
 }
 
+// readDirectoryDBML processes all .dbml files in directory
+// Returns merged Database model
+func (r *Reader) readDirectoryDBML(dirPath string) (*models.Database, error) {
+	// Discover and sort DBML files
+	files, err := r.discoverDBMLFiles(dirPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to discover DBML files: %w", err)
+	}
+
+	// If no files found, return empty database
+	if len(files) == 0 {
+		db := models.InitDatabase("database")
+		if r.options.Metadata != nil {
+			if name, ok := r.options.Metadata["name"].(string); ok {
+				db.Name = name
+			}
+		}
+		return db, nil
+	}
+
+	// Initialize database (will be merged with files)
+	var db *models.Database
+
+	// Process each file in sorted order
+	for _, filePath := range files {
+		content, err := os.ReadFile(filePath)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read file %s: %w", filePath, err)
+		}
+
+		fileDB, err := r.parseDBML(string(content))
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse file %s: %w", filePath, err)
+		}
+
+		// First file initializes the database
+		if db == nil {
+			db = fileDB
+		} else {
+			// Subsequent files are merged
+			mergeDatabase(db, fileDB)
+		}
+	}
+
+	return db, nil
+}
+
 // stripQuotes removes surrounding quotes from an identifier
 func stripQuotes(s string) string {
 	s = strings.TrimSpace(s)
@@ -76,6 +137,235 @@ func stripQuotes(s string) string {
 	return s
 }
 
+// parseFilePrefix extracts numeric prefix from filename
+// Examples: "1_schema.dbml" -> (1, true), "tables.dbml" -> (0, false)
+func parseFilePrefix(filename string) (int, bool) {
+	base := filepath.Base(filename)
+	re := regexp.MustCompile(`^(\d+)[_-]`)
+	matches := re.FindStringSubmatch(base)
+	if len(matches) > 1 {
+		var prefix int
+		_, err := fmt.Sscanf(matches[1], "%d", &prefix)
+		if err == nil {
+			return prefix, true
+		}
+	}
+	return 0, false
+}
+
+// hasCommentedRefs scans file content for commented-out Ref statements
+// Returns true if file contains lines like: // Ref: table.col > other.col
+func hasCommentedRefs(filePath string) (bool, error) {
+	content, err := os.ReadFile(filePath)
+	if err != nil {
+		return false, err
+	}
+
+	scanner := bufio.NewScanner(strings.NewReader(string(content)))
+	commentedRefRegex := regexp.MustCompile(`^\s*//.*Ref:\s+`)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		if commentedRefRegex.MatchString(line) {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}
+
+// discoverDBMLFiles finds all .dbml files in directory and returns them sorted
+func (r *Reader) discoverDBMLFiles(dirPath string) ([]string, error) {
+	pattern := filepath.Join(dirPath, "*.dbml")
+	files, err := filepath.Glob(pattern)
+	if err != nil {
+		return nil, fmt.Errorf("failed to glob .dbml files: %w", err)
+	}
+
+	return sortDBMLFiles(files), nil
+}
+
+// sortDBMLFiles sorts files by:
+// 1. Files without commented refs (by numeric prefix, then alphabetically)
+// 2. Files with commented refs (by numeric prefix, then alphabetically)
+func sortDBMLFiles(files []string) []string {
+	// Create a slice to hold file info for sorting
+	type fileInfo struct {
+		path         string
+		hasCommented bool
+		prefix       int
+		hasPrefix    bool
+		basename     string
+	}
+
+	fileInfos := make([]fileInfo, 0, len(files))
+
+	for _, file := range files {
+		hasCommented, err := hasCommentedRefs(file)
+		if err != nil {
+			// If we can't read the file, treat it as not having commented refs
+			hasCommented = false
+		}
+
+		prefix, hasPrefix := parseFilePrefix(file)
+		basename := filepath.Base(file)
+
+		fileInfos = append(fileInfos, fileInfo{
+			path:         file,
+			hasCommented: hasCommented,
+			prefix:       prefix,
+			hasPrefix:    hasPrefix,
+			basename:     basename,
+		})
+	}
+
+	// Sort by: hasCommented (false first), hasPrefix (true first), prefix, basename
+	sort.Slice(fileInfos, func(i, j int) bool {
+		// First, sort by commented refs (files without commented refs come first)
+		if fileInfos[i].hasCommented != fileInfos[j].hasCommented {
+			return !fileInfos[i].hasCommented
+		}
+
+		// Then by presence of prefix (files with prefix come first)
+		if fileInfos[i].hasPrefix != fileInfos[j].hasPrefix {
+			return fileInfos[i].hasPrefix
+		}
+
+		// If both have prefix, sort by prefix value
+		if fileInfos[i].hasPrefix && fileInfos[j].hasPrefix {
+			if fileInfos[i].prefix != fileInfos[j].prefix {
+				return fileInfos[i].prefix < fileInfos[j].prefix
+			}
+		}
+
+		// Finally, sort alphabetically by basename
+		return fileInfos[i].basename < fileInfos[j].basename
+	})
+
+	// Extract sorted paths
+	sortedFiles := make([]string, len(fileInfos))
+	for i, info := range fileInfos {
+		sortedFiles[i] = info.path
+	}
+
+	return sortedFiles
+}
+
+// mergeTable combines two table definitions
+// Merges: Columns (map), Constraints (map), Indexes (map), Relationships (map)
+// Uses first non-empty Description
+func mergeTable(baseTable, fileTable *models.Table) {
+	// Merge columns (map naturally merges - later keys overwrite)
+	for key, col := range fileTable.Columns {
+		baseTable.Columns[key] = col
+	}
+
+	// Merge constraints
+	for key, constraint := range fileTable.Constraints {
+		baseTable.Constraints[key] = constraint
+	}
+
+	// Merge indexes
+	for key, index := range fileTable.Indexes {
+		baseTable.Indexes[key] = index
+	}
+
+	// Merge relationships
+	for key, rel := range fileTable.Relationships {
+		baseTable.Relationships[key] = rel
+	}
+
+	// Use first non-empty description
+	if baseTable.Description == "" && fileTable.Description != "" {
+		baseTable.Description = fileTable.Description
+	}
+
+	// Merge metadata maps
+	if baseTable.Metadata == nil {
+		baseTable.Metadata = make(map[string]any)
+	}
+	for key, val := range fileTable.Metadata {
+		baseTable.Metadata[key] = val
+	}
+}
+
+// mergeSchema finds or creates schema and merges tables
+func mergeSchema(baseDB *models.Database, fileSchema *models.Schema) {
+	// Find existing schema by name (normalize names by stripping quotes)
+	var existingSchema *models.Schema
+	fileSchemaName := stripQuotes(fileSchema.Name)
+	for _, schema := range baseDB.Schemas {
+		if stripQuotes(schema.Name) == fileSchemaName {
+			existingSchema = schema
+			break
+		}
+	}
+
+	// If schema doesn't exist, add it and return
+	if existingSchema == nil {
+		baseDB.Schemas = append(baseDB.Schemas, fileSchema)
+		return
+	}
+
+	// Merge tables from fileSchema into existingSchema
+	for _, fileTable := range fileSchema.Tables {
+		// Find existing table by name (normalize names by stripping quotes)
+		var existingTable *models.Table
+		fileTableName := stripQuotes(fileTable.Name)
+		for _, table := range existingSchema.Tables {
+			if stripQuotes(table.Name) == fileTableName {
+				existingTable = table
+				break
+			}
+		}
+
+		// If table doesn't exist, add it
+		if existingTable == nil {
+			existingSchema.Tables = append(existingSchema.Tables, fileTable)
+		} else {
+			// Merge table properties - tables are identical, skip
+			mergeTable(existingTable, fileTable)
+		}
+	}
+
+	// Merge other schema properties
+	existingSchema.Views = append(existingSchema.Views, fileSchema.Views...)
+	existingSchema.Sequences = append(existingSchema.Sequences, fileSchema.Sequences...)
+	existingSchema.Scripts = append(existingSchema.Scripts, fileSchema.Scripts...)
+
+	// Merge permissions
+	if existingSchema.Permissions == nil {
+		existingSchema.Permissions = make(map[string]string)
+	}
+	for key, val := range fileSchema.Permissions {
+		existingSchema.Permissions[key] = val
+	}
+
+	// Merge metadata
+	if existingSchema.Metadata == nil {
+		existingSchema.Metadata = make(map[string]any)
+	}
+	for key, val := range fileSchema.Metadata {
+		existingSchema.Metadata[key] = val
+	}
+}
+
+// mergeDatabase merges schemas from fileDB into baseDB
+func mergeDatabase(baseDB, fileDB *models.Database) {
+	// Merge each schema from fileDB
+	for _, fileSchema := range fileDB.Schemas {
+		mergeSchema(baseDB, fileSchema)
+	}
+
+	// Merge domains
+	baseDB.Domains = append(baseDB.Domains, fileDB.Domains...)
+
+	// Use first non-empty description
+	if baseDB.Description == "" && fileDB.Description != "" {
+		baseDB.Description = fileDB.Description
+	}
+}
+
 // parseDBML parses DBML content and returns a Database model
 func (r *Reader) parseDBML(content string) (*models.Database, error) {
 	db := models.InitDatabase("database")
@@ -332,29 +622,33 @@ func (r *Reader) parseIndex(line, tableName, schemaName string) *models.Index {
 	// Format: (columns) [attributes] OR columnname [attributes]
 	var columns []string
 
-	if strings.Contains(line, "(") && strings.Contains(line, ")") {
+	// Find the attributes section to avoid parsing parentheses in notes/attributes
+	attrStart := strings.Index(line, "[")
+	columnPart := line
+	if attrStart > 0 {
+		columnPart = line[:attrStart]
+	}
+
+	if strings.Contains(columnPart, "(") && strings.Contains(columnPart, ")") {
 		// Multi-column format: (col1, col2) [attributes]
-		colStart := strings.Index(line, "(")
-		colEnd := strings.Index(line, ")")
+		colStart := strings.Index(columnPart, "(")
+		colEnd := strings.Index(columnPart, ")")
 		if colStart >= colEnd {
 			return nil
 		}
 
-		columnsStr := line[colStart+1 : colEnd]
+		columnsStr := columnPart[colStart+1 : colEnd]
 		for _, col := range strings.Split(columnsStr, ",") {
 			columns = append(columns, stripQuotes(strings.TrimSpace(col)))
 		}
-	} else if strings.Contains(line, "[") {
+	} else if attrStart > 0 {
 		// Single column format: columnname [attributes]
 		// Extract column name before the bracket
-		idx := strings.Index(line, "[")
-		if idx > 0 {
-			colName := strings.TrimSpace(line[:idx])
+		colName := strings.TrimSpace(columnPart)
 		if colName != "" {
 			columns = []string{stripQuotes(colName)}
 		}
 	}
-	}
 
 	if len(columns) == 0 {
 		return nil

pkg/readers/dbml/reader_test.go

@@ -1,6 +1,7 @@
 package dbml
 
 import (
+	"os"
 	"path/filepath"
 	"testing"
 
@@ -517,3 +518,286 @@ func TestGetForeignKeys(t *testing.T) {
 		t.Error("Expected foreign key constraint type")
 	}
 }
+
+// Tests for multi-file directory loading
+
+func TestReadDirectory_MultipleFiles(t *testing.T) {
+	opts := &readers.ReaderOptions{
+		FilePath: filepath.Join("..", "..", "..", "tests", "assets", "dbml", "multifile"),
+	}
+
+	reader := NewReader(opts)
+	db, err := reader.ReadDatabase()
+	if err != nil {
+		t.Fatalf("ReadDatabase() error = %v", err)
+	}
+
+	if db == nil {
+		t.Fatal("ReadDatabase() returned nil database")
+	}
+
+	// Should have public schema
+	if len(db.Schemas) == 0 {
+		t.Fatal("Expected at least one schema")
+	}
+
+	var publicSchema *models.Schema
+	for _, schema := range db.Schemas {
+		if schema.Name == "public" {
+			publicSchema = schema
+			break
+		}
+	}
+
+	if publicSchema == nil {
+		t.Fatal("Public schema not found")
+	}
+
+	// Should have 3 tables: users, posts, comments
+	if len(publicSchema.Tables) != 3 {
+		t.Fatalf("Expected 3 tables, got %d", len(publicSchema.Tables))
+	}
+
+	// Find tables
+	var usersTable, postsTable, commentsTable *models.Table
+	for _, table := range publicSchema.Tables {
+		switch table.Name {
+		case "users":
+			usersTable = table
+		case "posts":
+			postsTable = table
+		case "comments":
+			commentsTable = table
+		}
+	}
+
+	if usersTable == nil {
+		t.Fatal("Users table not found")
+	}
+	if postsTable == nil {
+		t.Fatal("Posts table not found")
+	}
+	if commentsTable == nil {
+		t.Fatal("Comments table not found")
+	}
+
+	// Verify users table has merged columns from 1_users.dbml and 3_add_columns.dbml
+	expectedUserColumns := []string{"id", "email", "name", "created_at"}
+	if len(usersTable.Columns) != len(expectedUserColumns) {
+		t.Errorf("Expected %d columns in users table, got %d", len(expectedUserColumns), len(usersTable.Columns))
+	}
+
+	for _, colName := range expectedUserColumns {
+		if _, exists := usersTable.Columns[colName]; !exists {
+			t.Errorf("Expected column '%s' in users table", colName)
+		}
+	}
+
+	// Verify posts table columns
+	expectedPostColumns := []string{"id", "user_id", "title", "content", "created_at"}
+	for _, colName := range expectedPostColumns {
+		if _, exists := postsTable.Columns[colName]; !exists {
+			t.Errorf("Expected column '%s' in posts table", colName)
+		}
+	}
+}
+
+func TestReadDirectory_TableMerging(t *testing.T) {
+	opts := &readers.ReaderOptions{
+		FilePath: filepath.Join("..", "..", "..", "tests", "assets", "dbml", "multifile"),
+	}
+
+	reader := NewReader(opts)
+	db, err := reader.ReadDatabase()
+	if err != nil {
+		t.Fatalf("ReadDatabase() error = %v", err)
+	}
+
+	// Find users table
+	var usersTable *models.Table
+	for _, schema := range db.Schemas {
+		for _, table := range schema.Tables {
+			if table.Name == "users" && schema.Name == "public" {
+				usersTable = table
+				break
+			}
+		}
+	}
+
+	if usersTable == nil {
+		t.Fatal("Users table not found")
+	}
+
+	// Verify columns from file 1 (id, email)
+	if _, exists := usersTable.Columns["id"]; !exists {
+		t.Error("Column 'id' from 1_users.dbml not found")
+	}
+	if _, exists := usersTable.Columns["email"]; !exists {
+		t.Error("Column 'email' from 1_users.dbml not found")
+	}
+
+	// Verify columns from file 3 (name, created_at)
+	if _, exists := usersTable.Columns["name"]; !exists {
+		t.Error("Column 'name' from 3_add_columns.dbml not found")
+	}
+	if _, exists := usersTable.Columns["created_at"]; !exists {
+		t.Error("Column 'created_at' from 3_add_columns.dbml not found")
+	}
+
+	// Verify column properties from file 1
+	emailCol := usersTable.Columns["email"]
+	if !emailCol.NotNull {
+		t.Error("Email column should be not null (from 1_users.dbml)")
+	}
+	if emailCol.Type != "varchar(255)" {
+		t.Errorf("Expected email type 'varchar(255)', got '%s'", emailCol.Type)
+	}
+}
+
+func TestReadDirectory_CommentedRefsLast(t *testing.T) {
+	// This test verifies that files with commented refs are processed last
+	// by checking that the file discovery returns them in the correct order
+	dirPath := filepath.Join("..", "..", "..", "tests", "assets", "dbml", "multifile")
+
+	opts := &readers.ReaderOptions{
+		FilePath: dirPath,
+	}
+
+	reader := NewReader(opts)
+	files, err := reader.discoverDBMLFiles(dirPath)
+	if err != nil {
+		t.Fatalf("discoverDBMLFiles() error = %v", err)
+	}
+
+	if len(files) < 2 {
+		t.Skip("Not enough files to test ordering")
+	}
+
+	// Check that 9_refs.dbml (which has commented refs) comes last
+	lastFile := filepath.Base(files[len(files)-1])
+	if lastFile != "9_refs.dbml" {
+		t.Errorf("Expected last file to be '9_refs.dbml' (has commented refs), got '%s'", lastFile)
+	}
+
+	// Check that numbered files without commented refs come first
+	firstFile := filepath.Base(files[0])
+	if firstFile != "1_users.dbml" {
+		t.Errorf("Expected first file to be '1_users.dbml', got '%s'", firstFile)
+	}
+}
+
+func TestReadDirectory_EmptyDirectory(t *testing.T) {
+	// Create a temporary empty directory
+	tmpDir := filepath.Join("..", "..", "..", "tests", "assets", "dbml", "empty_test_dir")
+	err := os.MkdirAll(tmpDir, 0755)
+	if err != nil {
+		t.Fatalf("Failed to create temp directory: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	opts := &readers.ReaderOptions{
+		FilePath: tmpDir,
+	}
+
+	reader := NewReader(opts)
+	db, err := reader.ReadDatabase()
+	if err != nil {
+		t.Fatalf("ReadDatabase() should not error on empty directory, got: %v", err)
+	}
+
+	if db == nil {
+		t.Fatal("ReadDatabase() returned nil database")
+	}
+
+	// Empty directory should return empty database
+	if len(db.Schemas) != 0 {
+		t.Errorf("Expected 0 schemas for empty directory, got %d", len(db.Schemas))
+	}
+}
+
+func TestReadDatabase_BackwardCompat(t *testing.T) {
+	// Test that single file loading still works
+	opts := &readers.ReaderOptions{
+		FilePath: filepath.Join("..", "..", "..", "tests", "assets", "dbml", "simple.dbml"),
+	}
+
+	reader := NewReader(opts)
+	db, err := reader.ReadDatabase()
+	if err != nil {
+		t.Fatalf("ReadDatabase() error = %v", err)
+	}
+
+	if db == nil {
+		t.Fatal("ReadDatabase() returned nil database")
+	}
+
+	if len(db.Schemas) == 0 {
+		t.Fatal("Expected at least one schema")
+	}
+
+	schema := db.Schemas[0]
+	if len(schema.Tables) != 1 {
+		t.Fatalf("Expected 1 table, got %d", len(schema.Tables))
+	}
+
+	table := schema.Tables[0]
+	if table.Name != "users" {
+		t.Errorf("Expected table name 'users', got '%s'", table.Name)
+	}
+}
+
+func TestParseFilePrefix(t *testing.T) {
+	tests := []struct {
+		filename   string
+		wantPrefix int
+		wantHas    bool
+	}{
+		{"1_schema.dbml", 1, true},
+		{"2_tables.dbml", 2, true},
+		{"10_relationships.dbml", 10, true},
+		{"99_data.dbml", 99, true},
+		{"schema.dbml", 0, false},
+		{"tables_no_prefix.dbml", 0, false},
+		{"/path/to/1_file.dbml", 1, true},
+		{"/path/to/file.dbml", 0, false},
+		{"1-file.dbml", 1, true},
+		{"2-another.dbml", 2, true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.filename, func(t *testing.T) {
+			gotPrefix, gotHas := parseFilePrefix(tt.filename)
+			if gotPrefix != tt.wantPrefix {
+				t.Errorf("parseFilePrefix(%s) prefix = %d, want %d", tt.filename, gotPrefix, tt.wantPrefix)
+			}
+			if gotHas != tt.wantHas {
+				t.Errorf("parseFilePrefix(%s) hasPrefix = %v, want %v", tt.filename, gotHas, tt.wantHas)
+			}
+		})
+	}
+}
+
+func TestHasCommentedRefs(t *testing.T) {
+	// Test with the actual multifile test fixtures
+	tests := []struct {
+		filename string
+		wantHas  bool
+	}{
+		{filepath.Join("..", "..", "..", "tests", "assets", "dbml", "multifile", "1_users.dbml"), false},
+		{filepath.Join("..", "..", "..", "tests", "assets", "dbml", "multifile", "2_posts.dbml"), false},
+		{filepath.Join("..", "..", "..", "tests", "assets", "dbml", "multifile", "3_add_columns.dbml"), false},
+		{filepath.Join("..", "..", "..", "tests", "assets", "dbml", "multifile", "9_refs.dbml"), true},
+	}
+
+	for _, tt := range tests {
+		t.Run(filepath.Base(tt.filename), func(t *testing.T) {
+			gotHas, err := hasCommentedRefs(tt.filename)
+			if err != nil {
+				t.Fatalf("hasCommentedRefs() error = %v", err)
+			}
+			if gotHas != tt.wantHas {
+				t.Errorf("hasCommentedRefs(%s) = %v, want %v", filepath.Base(tt.filename), gotHas, tt.wantHas)
+			}
+		})
+	}
+}

pkg/readers/dctx/reader.go

@@ -79,6 +79,8 @@ func (r *Reader) convertToDatabase(dctx *models.DCTXDictionary) (*models.Databas
 	db := models.InitDatabase(dbName)
 	schema := models.InitSchema("public")
 
+	// Note: DCTX doesn't have database GUID, but schema can use dictionary name if available
+
 	// Create GUID mappings for tables and keys
 	tableGuidMap := make(map[string]string)             // GUID -> table name
 	keyGuidMap := make(map[string]*models.DCTXKey)      // GUID -> key definition
@@ -162,6 +164,10 @@ func (r *Reader) convertTable(dctxTable *models.DCTXTable) (*models.Table, map[s
 	tableName := r.sanitizeName(dctxTable.Name)
 	table := models.InitTable(tableName, "public")
 	table.Description = dctxTable.Description
+	// Assign GUID from DCTX table
+	if dctxTable.Guid != "" {
+		table.GUID = dctxTable.Guid
+	}
 
 	fieldGuidMap := make(map[string]string)
 
@@ -202,6 +208,10 @@ func (r *Reader) convertField(dctxField *models.DCTXField, tableName string) ([]
 
 	// Convert single field
 	column := models.InitColumn(r.sanitizeName(dctxField.Name), tableName, "public")
+	// Assign GUID from DCTX field
+	if dctxField.Guid != "" {
+		column.GUID = dctxField.Guid
+	}
 
 	// Map Clarion data types
 	dataType, length := r.mapDataType(dctxField.DataType, dctxField.Size)
@@ -346,6 +356,10 @@ func (r *Reader) convertKey(dctxKey *models.DCTXKey, table *models.Table, fieldG
 		constraint.Table = table.Name
 		constraint.Schema = table.Schema
 		constraint.Columns = columns
+		// Assign GUID from DCTX key
+		if dctxKey.Guid != "" {
+			constraint.GUID = dctxKey.Guid
+		}
 
 		table.Constraints[constraint.Name] = constraint
 
@@ -366,6 +380,10 @@ func (r *Reader) convertKey(dctxKey *models.DCTXKey, table *models.Table, fieldG
 	index.Columns = columns
 	index.Unique = dctxKey.Unique
 	index.Type = "btree"
+	// Assign GUID from DCTX key
+	if dctxKey.Guid != "" {
+		index.GUID = dctxKey.Guid
+	}
 
 	table.Indexes[index.Name] = index
 	return nil
@@ -460,6 +478,10 @@ func (r *Reader) processRelations(dctx *models.DCTXDictionary, schema *models.Sc
 		constraint.ReferencedColumns = pkColumns
 		constraint.OnDelete = r.mapReferentialAction(relation.Delete)
 		constraint.OnUpdate = r.mapReferentialAction(relation.Update)
+		// Assign GUID from DCTX relation
+		if relation.Guid != "" {
+			constraint.GUID = relation.Guid
+		}
 
 		foreignTable.Constraints[fkName] = constraint
 
@@ -473,6 +495,10 @@ func (r *Reader) processRelations(dctx *models.DCTXDictionary, schema *models.Sc
 		relationship.ForeignKey = fkName
 		relationship.Properties["on_delete"] = constraint.OnDelete
 		relationship.Properties["on_update"] = constraint.OnUpdate
+		// Assign GUID from DCTX relation
+		if relation.Guid != "" {
+			relationship.GUID = relation.Guid
+		}
 
 		foreignTable.Relationships[relationshipName] = relationship
 	}

pkg/readers/drizzle/reader.go

@@ -241,11 +241,9 @@ func (r *Reader) parsePgEnum(line string, matches []string) *models.Enum {
 		}
 	}
 
-	return &models.Enum{
-		Name:   enumName,
-		Values: values,
-		Schema: "public",
-	}
+	enum := models.InitEnum(enumName, "public")
+	enum.Values = values
+	return enum
 }
 
 // parseTableBlock parses a complete pgTable definition block

pkg/readers/graphql/reader.go

@@ -260,11 +260,7 @@ func (r *Reader) parseType(typeName string, lines []string, schema *models.Schem
 }
 
 func (r *Reader) parseEnum(enumName string, lines []string, schema *models.Schema) {
-	enum := &models.Enum{
-		Name:   enumName,
-		Schema: schema.Name,
-		Values: make([]string, 0),
-	}
+	enum := models.InitEnum(enumName, schema.Name)
 
 	for _, line := range lines {
 		trimmed := strings.TrimSpace(line)

pkg/readers/prisma/reader.go

@@ -128,11 +128,7 @@ func (r *Reader) parsePrisma(content string) (*models.Database, error) {
 		if matches := enumRegex.FindStringSubmatch(trimmed); matches != nil {
 			currentBlock = "enum"
 			enumName := matches[1]
-			currentEnum = &models.Enum{
-				Name:   enumName,
-				Schema: "public",
-				Values: make([]string, 0),
-			}
+			currentEnum = models.InitEnum(enumName, "public")
 			blockContent = []string{}
 			continue
 		}

pkg/readers/sqldir/reader.go

@@ -150,13 +150,11 @@ func (r *Reader) readScripts() ([]*models.Script, error) {
 		}
 
 		// Create Script model
-		script := &models.Script{
-			Name:        name,
-			Description: fmt.Sprintf("SQL script from %s", relPath),
-			SQL:         string(content),
-			Priority:    priority,
-			Sequence:    uint(sequence),
-		}
+		script := models.InitScript(name)
+		script.Description = fmt.Sprintf("SQL script from %s", relPath)
+		script.SQL = string(content)
+		script.Priority = priority
+		script.Sequence = uint(sequence)
 
 		scripts = append(scripts, script)
 

pkg/ui/column_screens.go

@@ -23,6 +23,7 @@ func (se *SchemaEditor) showColumnEditor(schemaIndex, tableIndex, colIndex int,
 	newIsNotNull := column.NotNull
 	newDefault := column.Default
 	newDescription := column.Description
+	newGUID := column.GUID
 
 	// Column type options: PostgreSQL, MySQL, SQL Server, and common SQL types
 	columnTypes := []string{
@@ -94,9 +95,14 @@ func (se *SchemaEditor) showColumnEditor(schemaIndex, tableIndex, colIndex int,
 		newDescription = value
 	})
 
+	form.AddInputField("GUID", column.GUID, 40, nil, func(value string) {
+		newGUID = value
+	})
+
 	form.AddButton("Save", func() {
 		// Apply changes using dataops
 		se.UpdateColumn(schemaIndex, tableIndex, originalName, newName, newType, newIsPK, newIsNotNull, newDefault, newDescription)
+		se.db.Schemas[schemaIndex].Tables[tableIndex].Columns[newName].GUID = newGUID
 
 		se.pages.RemovePage("column-editor")
 		se.pages.SwitchToPage("table-editor")

pkg/ui/database_screens.go

@@ -14,6 +14,7 @@ func (se *SchemaEditor) showEditDatabaseForm() {
 	dbComment := se.db.Comment
 	dbType := string(se.db.DatabaseType)
 	dbVersion := se.db.DatabaseVersion
+	dbGUID := se.db.GUID
 
 	// Database type options
 	dbTypeOptions := []string{"pgsql", "mssql", "sqlite"}
@@ -45,11 +46,16 @@ func (se *SchemaEditor) showEditDatabaseForm() {
 		dbVersion = value
 	})
 
+	form.AddInputField("GUID", dbGUID, 40, nil, func(value string) {
+		dbGUID = value
+	})
+
 	form.AddButton("Save", func() {
 		if dbName == "" {
 			return
 		}
 		se.updateDatabase(dbName, dbDescription, dbComment, dbType, dbVersion)
+		se.db.GUID = dbGUID
 		se.pages.RemovePage("edit-database")
 		se.pages.RemovePage("main")
 		se.pages.AddPage("main", se.createMainMenu(), true, true)

pkg/ui/load_save_screens.go

@@ -4,10 +4,12 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/gdamore/tcell/v2"
 	"github.com/rivo/tview"
 
+	"git.warky.dev/wdevs/relspecgo/pkg/merge"
 	"git.warky.dev/wdevs/relspecgo/pkg/models"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers"
 	rbun "git.warky.dev/wdevs/relspecgo/pkg/readers/bun"
@@ -107,8 +109,7 @@ func (se *SchemaEditor) showLoadScreen() {
 
 	// Keyboard shortcuts
 	form.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
-		switch event.Key() {
-		case tcell.KeyEscape:
+		if event.Key() == tcell.KeyEscape {
 			se.app.Stop()
 			return nil
 		}
@@ -214,8 +215,7 @@ func (se *SchemaEditor) showSaveScreen() {
 
 	// Keyboard shortcuts
 	form.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
-		switch event.Key() {
-		case tcell.KeyEscape:
+		if event.Key() == tcell.KeyEscape {
 			se.pages.RemovePage("save-database")
 			se.pages.SwitchToPage("main")
 			return nil
@@ -524,3 +524,268 @@ Examples:
   - File: ~/schemas/mydb.dbml
   - Directory (for code formats): ./models/`
 }
+
+// showImportScreen displays the import/merge database screen
+func (se *SchemaEditor) showImportScreen() {
+	flex := tview.NewFlex().SetDirection(tview.FlexRow)
+
+	// Title
+	title := tview.NewTextView().
+		SetText("[::b]Import & Merge Database Schema").
+		SetTextAlign(tview.AlignCenter).
+		SetDynamicColors(true)
+
+	// Form
+	form := tview.NewForm()
+	form.SetBorder(true).SetTitle(" Import Configuration ").SetTitleAlign(tview.AlignLeft)
+
+	// Format selection
+	formatOptions := []string{
+		"dbml", "dctx", "drawdb", "graphql", "json", "yaml",
+		"gorm", "bun", "drizzle", "prisma", "typeorm", "pgsql",
+	}
+	selectedFormat := 0
+	currentFormat := formatOptions[selectedFormat]
+
+	// File path input
+	filePath := ""
+	connString := ""
+	skipDomains := false
+	skipRelations := false
+	skipEnums := false
+	skipViews := false
+	skipSequences := false
+	skipTables := ""
+
+	form.AddDropDown("Format", formatOptions, 0, func(option string, index int) {
+		selectedFormat = index
+		currentFormat = option
+	})
+
+	form.AddInputField("File Path", "", 50, nil, func(value string) {
+		filePath = value
+	})
+
+	form.AddInputField("Connection String", "", 50, nil, func(value string) {
+		connString = value
+	})
+
+	form.AddInputField("Skip Tables (comma-separated)", "", 50, nil, func(value string) {
+		skipTables = value
+	})
+
+	form.AddCheckbox("Skip Domains", false, func(checked bool) {
+		skipDomains = checked
+	})
+
+	form.AddCheckbox("Skip Relations", false, func(checked bool) {
+		skipRelations = checked
+	})
+
+	form.AddCheckbox("Skip Enums", false, func(checked bool) {
+		skipEnums = checked
+	})
+
+	form.AddCheckbox("Skip Views", false, func(checked bool) {
+		skipViews = checked
+	})
+
+	form.AddCheckbox("Skip Sequences", false, func(checked bool) {
+		skipSequences = checked
+	})
+
+	form.AddTextView("Help", getImportHelpText(), 0, 7, true, false)
+
+	// Buttons
+	form.AddButton("Import & Merge [i]", func() {
+		se.importAndMergeDatabase(currentFormat, filePath, connString, skipDomains, skipRelations, skipEnums, skipViews, skipSequences, skipTables)
+	})
+
+	form.AddButton("Back [b]", func() {
+		se.pages.RemovePage("import-database")
+		se.pages.SwitchToPage("main")
+	})
+
+	form.AddButton("Exit [q]", func() {
+		se.app.Stop()
+	})
+
+	// Keyboard shortcuts
+	form.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
+		if event.Key() == tcell.KeyEscape {
+			se.pages.RemovePage("import-database")
+			se.pages.SwitchToPage("main")
+			return nil
+		}
+		switch event.Rune() {
+		case 'i':
+			se.importAndMergeDatabase(currentFormat, filePath, connString, skipDomains, skipRelations, skipEnums, skipViews, skipSequences, skipTables)
+			return nil
+		case 'b':
+			se.pages.RemovePage("import-database")
+			se.pages.SwitchToPage("main")
+			return nil
+		case 'q':
+			se.app.Stop()
+			return nil
+		}
+		return event
+	})
+
+	flex.AddItem(title, 1, 0, false).
+		AddItem(form, 0, 1, true)
+
+	se.pages.AddAndSwitchToPage("import-database", flex, true)
+}
+
+// importAndMergeDatabase imports and merges a database from the specified configuration
+func (se *SchemaEditor) importAndMergeDatabase(format, filePath, connString string, skipDomains, skipRelations, skipEnums, skipViews, skipSequences bool, skipTables string) {
+	// Validate input
+	if format == "pgsql" {
+		if connString == "" {
+			se.showErrorDialog("Error", "Connection string is required for PostgreSQL")
+			return
+		}
+	} else {
+		if filePath == "" {
+			se.showErrorDialog("Error", "File path is required for "+format)
+			return
+		}
+		// Expand home directory
+		if len(filePath) > 0 && filePath[0] == '~' {
+			home, err := os.UserHomeDir()
+			if err == nil {
+				filePath = filepath.Join(home, filePath[1:])
+			}
+		}
+	}
+
+	// Create reader
+	var reader readers.Reader
+	switch format {
+	case "dbml":
+		reader = rdbml.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "dctx":
+		reader = rdctx.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "drawdb":
+		reader = rdrawdb.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "graphql":
+		reader = rgraphql.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "json":
+		reader = rjson.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "yaml":
+		reader = ryaml.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "gorm":
+		reader = rgorm.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "bun":
+		reader = rbun.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "drizzle":
+		reader = rdrizzle.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "prisma":
+		reader = rprisma.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "typeorm":
+		reader = rtypeorm.NewReader(&readers.ReaderOptions{FilePath: filePath})
+	case "pgsql":
+		reader = rpgsql.NewReader(&readers.ReaderOptions{ConnectionString: connString})
+	default:
+		se.showErrorDialog("Error", "Unsupported format: "+format)
+		return
+	}
+
+	// Read the database to import
+	importDb, err := reader.ReadDatabase()
+	if err != nil {
+		se.showErrorDialog("Import Error", fmt.Sprintf("Failed to read database: %v", err))
+		return
+	}
+
+	// Show confirmation dialog
+	se.showImportConfirmation(importDb, skipDomains, skipRelations, skipEnums, skipViews, skipSequences, skipTables)
+}
+
+// showImportConfirmation shows a confirmation dialog before merging
+func (se *SchemaEditor) showImportConfirmation(importDb *models.Database, skipDomains, skipRelations, skipEnums, skipViews, skipSequences bool, skipTables string) {
+	confirmText := fmt.Sprintf("Import & Merge Database?\n\nSource: %s\nTarget: %s\n\nThis will add missing schemas, tables, columns, and other objects from the source to your database.\n\nExisting items will NOT be modified.",
+		importDb.Name, se.db.Name)
+
+	modal := tview.NewModal().
+		SetText(confirmText).
+		AddButtons([]string{"Cancel", "Merge"}).
+		SetDoneFunc(func(buttonIndex int, buttonLabel string) {
+			se.pages.RemovePage("import-confirm")
+			if buttonLabel == "Merge" {
+				se.performMerge(importDb, skipDomains, skipRelations, skipEnums, skipViews, skipSequences, skipTables)
+			}
+		})
+
+	modal.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
+		if event.Key() == tcell.KeyEscape {
+			se.pages.RemovePage("import-confirm")
+			se.pages.SwitchToPage("import-database")
+			return nil
+		}
+		return event
+	})
+
+	se.pages.AddAndSwitchToPage("import-confirm", modal, true)
+}
+
+// performMerge performs the actual merge operation
+func (se *SchemaEditor) performMerge(importDb *models.Database, skipDomains, skipRelations, skipEnums, skipViews, skipSequences bool, skipTables string) {
+	// Create merge options
+	opts := &merge.MergeOptions{
+		SkipDomains:   skipDomains,
+		SkipRelations: skipRelations,
+		SkipEnums:     skipEnums,
+		SkipViews:     skipViews,
+		SkipSequences: skipSequences,
+	}
+
+	// Parse skip tables
+	if skipTables != "" {
+		opts.SkipTableNames = parseSkipTablesUI(skipTables)
+	}
+
+	// Perform the merge
+	result := merge.MergeDatabases(se.db, importDb, opts)
+
+	// Update the database timestamp
+	se.db.UpdateDate()
+
+	// Show success dialog with summary
+	summary := merge.GetMergeSummary(result)
+	se.showSuccessDialog("Import Complete", summary, func() {
+		se.pages.RemovePage("import-database")
+		se.pages.RemovePage("main")
+		se.pages.AddPage("main", se.createMainMenu(), true, true)
+	})
+}
+
+// getImportHelpText returns the help text for the import screen
+func getImportHelpText() string {
+	return `Import & Merge: Adds missing schemas, tables, columns, and other objects to your existing database.
+
+File-based formats: dbml, dctx, drawdb, graphql, json, yaml, gorm, bun, drizzle, prisma, typeorm
+Database formats: pgsql (requires connection string)
+
+Skip options: Check to exclude specific object types from the merge.`
+}
+
+func parseSkipTablesUI(skipTablesStr string) map[string]bool {
+	skipTables := make(map[string]bool)
+	if skipTablesStr == "" {
+		return skipTables
+	}
+
+	// Split by comma and trim whitespace
+	parts := strings.Split(skipTablesStr, ",")
+	for _, part := range parts {
+		trimmed := strings.TrimSpace(part)
+		if trimmed != "" {
+			// Store in lowercase for case-insensitive matching
+			skipTables[strings.ToLower(trimmed)] = true
+		}
+	}
+
+	return skipTables
+}

pkg/ui/main_menu.go

@@ -39,6 +39,9 @@ func (se *SchemaEditor) createMainMenu() tview.Primitive {
 		AddItem("Manage Domains", "View, create, edit, and delete domains", 'd', func() {
 			se.showDomainList()
 		}).
+		AddItem("Import & Merge", "Import and merge schema from another database", 'i', func() {
+			se.showImportScreen()
+		}).
 		AddItem("Save Database", "Save database to file or database", 'w', func() {
 			se.showSaveScreen()
 		}).

pkg/ui/schema_screens.go

@@ -24,8 +24,8 @@ func (se *SchemaEditor) showSchemaList() {
 	schemaTable := tview.NewTable().SetBorders(true).SetSelectable(true, false).SetFixed(1, 0)
 
 	// Add header row with padding for full width
-	headers := []string{"Name", "Sequence", "Total Tables", "Total Sequences", "Total Views", "Description"}
-	headerWidths := []int{20, 15, 20, 20, 15} // Last column takes remaining space
+	headers := []string{"Name", "Sequence", "Total Tables", "Total Sequences", "Total Views", "GUID", "Description"}
+	headerWidths := []int{20, 15, 20, 20, 15, 36} // Last column takes remaining space
 	for i, header := range headers {
 		padding := ""
 		if i < len(headerWidths) {
@@ -67,9 +67,14 @@ func (se *SchemaEditor) showSchemaList() {
 		viewsCell := tview.NewTableCell(viewsStr).SetSelectable(true)
 		schemaTable.SetCell(row+1, 4, viewsCell)
 
+		// GUID - pad to 36 chars
+		guidStr := fmt.Sprintf("%-36s", schema.GUID)
+		guidCell := tview.NewTableCell(guidStr).SetSelectable(true)
+		schemaTable.SetCell(row+1, 5, guidCell)
+
 		// Description - no padding, takes remaining space
 		descCell := tview.NewTableCell(schema.Description).SetSelectable(true)
-		schemaTable.SetCell(row+1, 5, descCell)
+		schemaTable.SetCell(row+1, 6, descCell)
 	}
 
 	schemaTable.SetTitle(" Schemas ").SetBorder(true).SetTitleAlign(tview.AlignLeft)
@@ -307,6 +312,7 @@ func (se *SchemaEditor) showEditSchemaDialog(schemaIndex int) {
 	newName := schema.Name
 	newOwner := schema.Owner
 	newDescription := schema.Description
+	newGUID := schema.GUID
 
 	form.AddInputField("Schema Name", schema.Name, 40, nil, func(value string) {
 		newName = value
@@ -320,9 +326,14 @@ func (se *SchemaEditor) showEditSchemaDialog(schemaIndex int) {
 		newDescription = value
 	})
 
+	form.AddInputField("GUID", schema.GUID, 40, nil, func(value string) {
+		newGUID = value
+	})
+
 	form.AddButton("Save", func() {
 		// Apply changes using dataops
 		se.UpdateSchema(schemaIndex, newName, newOwner, newDescription)
+		se.db.Schemas[schemaIndex].GUID = newGUID
 
 		schema := se.db.Schemas[schemaIndex]
 		se.pages.RemovePage("edit-schema")

pkg/ui/table_screens.go

@@ -24,8 +24,8 @@ func (se *SchemaEditor) showTableList() {
 	tableTable := tview.NewTable().SetBorders(true).SetSelectable(true, false).SetFixed(1, 0)
 
 	// Add header row with padding for full width
-	headers := []string{"Name", "Schema", "Sequence", "Total Columns", "Total Relations", "Total Indexes", "Description", "Comment"}
-	headerWidths := []int{18, 15, 12, 14, 15, 14, 0, 12} // Description gets remainder
+	headers := []string{"Name", "Schema", "Sequence", "Total Columns", "Total Relations", "Total Indexes", "GUID", "Description", "Comment"}
+	headerWidths := []int{18, 15, 12, 14, 15, 14, 36, 0, 12} // Description gets remainder
 	for i, header := range headers {
 		padding := ""
 		if i < len(headerWidths) && headerWidths[i] > 0 {
@@ -82,14 +82,19 @@ func (se *SchemaEditor) showTableList() {
 		idxCell := tview.NewTableCell(idxStr).SetSelectable(true)
 		tableTable.SetCell(row+1, 5, idxCell)
 
+		// GUID - pad to 36 chars
+		guidStr := fmt.Sprintf("%-36s", table.GUID)
+		guidCell := tview.NewTableCell(guidStr).SetSelectable(true)
+		tableTable.SetCell(row+1, 6, guidCell)
+
 		// Description - no padding, takes remaining space
 		descCell := tview.NewTableCell(table.Description).SetSelectable(true)
-		tableTable.SetCell(row+1, 6, descCell)
+		tableTable.SetCell(row+1, 7, descCell)
 
 		// Comment - pad to 12 chars
 		commentStr := fmt.Sprintf("%-12s", table.Comment)
 		commentCell := tview.NewTableCell(commentStr).SetSelectable(true)
-		tableTable.SetCell(row+1, 7, commentCell)
+		tableTable.SetCell(row+1, 8, commentCell)
 	}
 
 	tableTable.SetTitle(" All Tables ").SetBorder(true).SetTitleAlign(tview.AlignLeft)
@@ -188,8 +193,8 @@ func (se *SchemaEditor) showTableEditor(schemaIndex, tableIndex int, table *mode
 	colTable := tview.NewTable().SetBorders(true).SetSelectable(true, false).SetFixed(1, 0)
 
 	// Add header row with padding for full width
-	headers := []string{"Name", "Type", "Default", "KeyType", "Description"}
-	headerWidths := []int{20, 18, 15, 15} // Last column takes remaining space
+	headers := []string{"Name", "Type", "Default", "KeyType", "GUID", "Description"}
+	headerWidths := []int{20, 18, 15, 15, 36} // Last column takes remaining space
 	for i, header := range headers {
 		padding := ""
 		if i < len(headerWidths) {
@@ -237,9 +242,14 @@ func (se *SchemaEditor) showTableEditor(schemaIndex, tableIndex int, table *mode
 		keyTypeCell := tview.NewTableCell(keyTypeStr).SetSelectable(true)
 		colTable.SetCell(row+1, 3, keyTypeCell)
 
+		// GUID - pad to 36 chars
+		guidStr := fmt.Sprintf("%-36s", column.GUID)
+		guidCell := tview.NewTableCell(guidStr).SetSelectable(true)
+		colTable.SetCell(row+1, 4, guidCell)
+
 		// Description
 		descCell := tview.NewTableCell(column.Description).SetSelectable(true)
-		colTable.SetCell(row+1, 4, descCell)
+		colTable.SetCell(row+1, 5, descCell)
 	}
 
 	colTable.SetTitle(" Columns ").SetBorder(true).SetTitleAlign(tview.AlignLeft)
@@ -490,6 +500,7 @@ func (se *SchemaEditor) showEditTableDialog(schemaIndex, tableIndex int) {
 	// Local variables to collect changes
 	newName := table.Name
 	newDescription := table.Description
+	newGUID := table.GUID
 
 	form.AddInputField("Table Name", table.Name, 40, nil, func(value string) {
 		newName = value
@@ -499,9 +510,14 @@ func (se *SchemaEditor) showEditTableDialog(schemaIndex, tableIndex int) {
 		newDescription = value
 	})
 
+	form.AddInputField("GUID", table.GUID, 40, nil, func(value string) {
+		newGUID = value
+	})
+
 	form.AddButton("Save", func() {
 		// Apply changes using dataops
 		se.UpdateTable(schemaIndex, tableIndex, newName, newDescription)
+		se.db.Schemas[schemaIndex].Tables[tableIndex].GUID = newGUID
 
 		table := se.db.Schemas[schemaIndex].Tables[tableIndex]
 		se.pages.RemovePage("edit-table")

pkg/writers/bun/type_mapper.go

@@ -192,8 +192,11 @@ func (tm *TypeMapper) BuildBunTag(column *models.Column, table *models.Table) st
 	}
 
 	// Nullable (Bun uses nullzero for nullable fields)
+	// and notnull tag for explicitly non-nullable fields
 	if !column.NotNull && !column.IsPrimaryKey {
 		parts = append(parts, "nullzero")
+	} else if column.NotNull && !column.IsPrimaryKey {
+		parts = append(parts, "notnull")
 	}
 
 	// Check for indexes (unique indexes should be added to tag)

pkg/writers/bun/writer.go

@@ -386,6 +386,7 @@ func (w *Writer) createDatabaseRef(db *models.Database) *models.Database {
 		DatabaseVersion: db.DatabaseVersion,
 		SourceFormat:    db.SourceFormat,
 		Schemas:         nil, // Don't include schemas to avoid circular reference
+		GUID:            db.GUID,
 	}
 }
 
@@ -402,5 +403,6 @@ func (w *Writer) createSchemaRef(schema *models.Schema, db *models.Database) *mo
 		Sequence:    schema.Sequence,
 		RefDatabase: w.createDatabaseRef(db), // Include database ref
 		Tables:      nil,                     // Don't include tables to avoid circular reference
+		GUID:        schema.GUID,
 	}
 }

pkg/writers/dbml/writer.go

@@ -126,7 +126,15 @@ func (w *Writer) tableToDBML(t *models.Table) string {
 			attrs = append(attrs, "increment")
 		}
 		if column.Default != nil {
-			attrs = append(attrs, fmt.Sprintf("default: `%v`", column.Default))
+			// Check if default value contains backticks (DBML expressions like `now()`)
+			defaultStr := fmt.Sprintf("%v", column.Default)
+			if strings.HasPrefix(defaultStr, "`") && strings.HasSuffix(defaultStr, "`") {
+				// Already an expression with backticks, use as-is
+				attrs = append(attrs, fmt.Sprintf("default: %s", defaultStr))
+			} else {
+				// Regular value, wrap in single quotes
+				attrs = append(attrs, fmt.Sprintf("default: '%v'", column.Default))
+			}
 		}
 
 		if len(attrs) > 0 {

pkg/writers/dctx/writer.go

@@ -133,7 +133,11 @@ func (w *Writer) mapTableFields(table *models.Table) models.DCTXTable {
 		prefix = table.Name[:3]
 	}
 
-	tableGuid := w.newGUID()
+	// Use GUID from model if available, otherwise generate a new one
+	tableGuid := table.GUID
+	if tableGuid == "" {
+		tableGuid = w.newGUID()
+	}
 	w.tableGuidMap[table.Name] = tableGuid
 
 	dctxTable := models.DCTXTable{
@@ -171,7 +175,11 @@ func (w *Writer) mapTableKeys(table *models.Table) []models.DCTXKey {
 }
 
 func (w *Writer) mapField(column *models.Column) models.DCTXField {
-	guid := w.newGUID()
+	// Use GUID from model if available, otherwise generate a new one
+	guid := column.GUID
+	if guid == "" {
+		guid = w.newGUID()
+	}
 	fieldKey := fmt.Sprintf("%s.%s", column.Table, column.Name)
 	w.fieldGuidMap[fieldKey] = guid
 
@@ -209,7 +217,11 @@ func (w *Writer) mapDataType(dataType string) string {
 }
 
 func (w *Writer) mapKey(index *models.Index, table *models.Table) models.DCTXKey {
-	guid := w.newGUID()
+	// Use GUID from model if available, otherwise generate a new one
+	guid := index.GUID
+	if guid == "" {
+		guid = w.newGUID()
+	}
 	keyKey := fmt.Sprintf("%s.%s", table.Name, index.Name)
 	w.keyGuidMap[keyKey] = guid
 
@@ -344,7 +356,7 @@ func (w *Writer) mapRelation(rel *models.Relationship, schema *models.Schema) mo
 	}
 
 	return models.DCTXRelation{
-		Guid:            w.newGUID(),
+		Guid:            rel.GUID,                      // Use GUID from relationship model
 		PrimaryTable:    w.tableGuidMap[rel.ToTable],   // GUID of the 'to' table (e.g., users)
 		ForeignTable:    w.tableGuidMap[rel.FromTable], // GUID of the 'from' table (e.g., posts)
 		PrimaryKey:      primaryKeyGUID,

pkg/writers/gorm/writer.go

@@ -380,6 +380,7 @@ func (w *Writer) createDatabaseRef(db *models.Database) *models.Database {
 		DatabaseVersion: db.DatabaseVersion,
 		SourceFormat:    db.SourceFormat,
 		Schemas:         nil, // Don't include schemas to avoid circular reference
+		GUID:            db.GUID,
 	}
 }
 
@@ -396,5 +397,6 @@ func (w *Writer) createSchemaRef(schema *models.Schema, db *models.Database) *mo
 		Sequence:    schema.Sequence,
 		RefDatabase: w.createDatabaseRef(db), // Include database ref
 		Tables:      nil,                     // Don't include tables to avoid circular reference
+		GUID:        schema.GUID,
 	}
 }

tests/assets/dbml/multifile/1_users.dbml

@@ -0,0 +1,5 @@
+// First file - users table basic structure
+Table public.users {
+  id bigint [pk, increment]
+  email varchar(255) [unique, not null]
+}

tests/assets/dbml/multifile/2_posts.dbml

@@ -0,0 +1,8 @@
+// Second file - posts table
+Table public.posts {
+  id bigint [pk, increment]
+  user_id bigint [not null]
+  title varchar(200) [not null]
+  content text
+  created_at timestamp [not null]
+}

tests/assets/dbml/multifile/3_add_columns.dbml

@@ -0,0 +1,5 @@
+// Third file - adds more columns to users table (tests merging)
+Table public.users {
+  name varchar(100)
+  created_at timestamp [not null]
+}

tests/assets/dbml/multifile/9_refs.dbml

@@ -0,0 +1,10 @@
+// File with commented-out refs - should load last
+// Contains relationships that depend on earlier tables
+
+// Ref: public.posts.user_id > public.users.id [ondelete: CASCADE]
+
+Table public.comments {
+  id bigint [pk, increment]
+  post_id bigint [not null]
+  content text [not null]
+}