feat(writer): 🎉 Implement add column statements for schema evolution

* Add functionality to generate ALTER TABLE ADD COLUMN statements for existing tables.
* Introduce tests for generating and writing add column statements.
* Enhance schema evolution capabilities when new columns are added.

.gitignore

@@ -47,3 +47,4 @@ dist/
 build/
 bin/
 tests/integration/failed_statements_example.txt
+test_output.log

cmd/relspec/scripts.go

@@ -39,8 +39,8 @@ Example filenames (hyphen format):
   1-002-create-posts.sql       # Priority 1, Sequence 2
   10-10-create-newid.pgsql     # Priority 10, Sequence 10
 
-Both formats can be mixed in the same directory.
+Both formats can be mixed in the same directory and subdirectories.
-Scripts are executed in order: Priority (ascending), then Sequence (ascending).`,
+Scripts are executed in order: Priority (ascending), Sequence (ascending), Name (alphabetical).`,
 }
 
 var scriptsListCmd = &cobra.Command{
@@ -48,8 +48,8 @@ var scriptsListCmd = &cobra.Command{
 	Short: "List SQL scripts from a directory",
 	Long: `List SQL scripts from a directory and show their execution order.
 
-The scripts are read from the specified directory and displayed in the order
+The scripts are read recursively from the specified directory and displayed in the order
-they would be executed (Priority ascending, then Sequence ascending).
+they would be executed: Priority (ascending), then Sequence (ascending), then Name (alphabetical).
 
 Example:
   relspec scripts list --dir ./migrations`,
@@ -61,10 +61,10 @@ var scriptsExecuteCmd = &cobra.Command{
 	Short: "Execute SQL scripts against a database",
 	Long: `Execute SQL scripts from a directory against a PostgreSQL database.
 
-Scripts are executed in order: Priority (ascending), then Sequence (ascending).
+Scripts are executed in order: Priority (ascending), Sequence (ascending), Name (alphabetical).
 Execution stops immediately on the first error.
 
-The directory is scanned recursively for files matching the patterns:
+The directory is scanned recursively for all subdirectories and files matching the patterns:
   {priority}_{sequence}_{name}.sql or .pgsql (underscore format)
   {priority}-{sequence}-{name}.sql or .pgsql (hyphen format)
 
@@ -75,7 +75,7 @@ PostgreSQL Connection String Examples:
   postgresql://user:pass@host/dbname?sslmode=require
 
 Examples:
-  # Execute migration scripts
+  # Execute migration scripts from a directory (including subdirectories)
   relspec scripts execute --dir ./migrations \
                           --conn "postgres://user:pass@localhost:5432/mydb"
 
@@ -149,7 +149,7 @@ func runScriptsList(cmd *cobra.Command, args []string) error {
 		return nil
 	}
 
-	// Sort scripts by Priority then Sequence
+	// Sort scripts by Priority, Sequence, then Name
 	sortedScripts := make([]*struct {
 		name     string
 		priority int
@@ -186,7 +186,10 @@ func runScriptsList(cmd *cobra.Command, args []string) error {
 		if sortedScripts[i].priority != sortedScripts[j].priority {
 			return sortedScripts[i].priority < sortedScripts[j].priority
 		}
-		return sortedScripts[i].sequence < sortedScripts[j].sequence
+		if sortedScripts[i].sequence != sortedScripts[j].sequence {
+			return sortedScripts[i].sequence < sortedScripts[j].sequence
+		}
+		return sortedScripts[i].name < sortedScripts[j].name
 	})
 
 	fmt.Fprintf(os.Stderr, "Found %d script(s) in execution order:\n\n", len(sortedScripts))
@@ -242,7 +245,7 @@ func runScriptsExecute(cmd *cobra.Command, args []string) error {
 	fmt.Fprintf(os.Stderr, "      ✓ Found %d script(s)\n\n", len(schema.Scripts))
 
 	// Step 2: Execute scripts
-	fmt.Fprintf(os.Stderr, "[2/2] Executing scripts in order (Priority → Sequence)...\n\n")
+	fmt.Fprintf(os.Stderr, "[2/2] Executing scripts in order (Priority → Sequence → Name)...\n\n")
 
 	writer := sqlexec.NewWriter(&writers.WriterOptions{
 		Metadata: map[string]any{

pkg/readers/sqldir/README.md

@@ -93,6 +93,7 @@ fmt.Printf("Found %d scripts\n", len(schema.Scripts))
 ## Features
 
 - **Recursive Directory Scanning**: Automatically scans all subdirectories
+- **Symlink Skipping**: Symbolic links are automatically skipped (prevents loops and duplicates)
 - **Multiple Extensions**: Supports both `.sql` and `.pgsql` files
 - **Flexible Naming**: Extract metadata from filename patterns
 - **Error Handling**: Validates directory existence and file accessibility
@@ -153,8 +154,9 @@ go test ./pkg/readers/sqldir/
 ```
 
 Tests include:
-- Valid file parsing
+- Valid file parsing (underscore and hyphen formats)
 - Recursive directory scanning
+- Symlink skipping
 - Invalid filename handling
 - Empty directory handling
 - Error conditions

pkg/readers/sqldir/reader.go

@@ -107,11 +107,20 @@ func (r *Reader) readScripts() ([]*models.Script, error) {
 			return err
 		}
 
-		// Skip directories
+		// Don't process directories as files (WalkDir still descends into them recursively)
 		if d.IsDir() {
 			return nil
 		}
 
+		// Skip symlinks
+		info, err := d.Info()
+		if err != nil {
+			return err
+		}
+		if info.Mode()&os.ModeSymlink != 0 {
+			return nil
+		}
+
 		// Get filename
 		filename := d.Name()
 

pkg/readers/sqldir/reader_test.go

@@ -373,3 +373,65 @@ func TestReader_MixedFormat(t *testing.T) {
 		}
 	}
 }
+
+func TestReader_SkipSymlinks(t *testing.T) {
+	// Create temporary test directory
+	tempDir, err := os.MkdirTemp("", "sqldir-test-symlink-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp directory: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	// Create a real SQL file
+	realFile := filepath.Join(tempDir, "1_001_real_file.sql")
+	if err := os.WriteFile(realFile, []byte("SELECT 1;"), 0644); err != nil {
+		t.Fatalf("Failed to create real file: %v", err)
+	}
+
+	// Create another file to link to
+	targetFile := filepath.Join(tempDir, "2_001_target.sql")
+	if err := os.WriteFile(targetFile, []byte("SELECT 2;"), 0644); err != nil {
+		t.Fatalf("Failed to create target file: %v", err)
+	}
+
+	// Create a symlink to the target file (this should be skipped)
+	symlinkFile := filepath.Join(tempDir, "3_001_symlink.sql")
+	if err := os.Symlink(targetFile, symlinkFile); err != nil {
+		// Skip test on systems that don't support symlinks (e.g., Windows without admin)
+		t.Skipf("Symlink creation not supported: %v", err)
+	}
+
+	// Create reader
+	reader := NewReader(&readers.ReaderOptions{
+		FilePath: tempDir,
+	})
+
+	// Read database
+	db, err := reader.ReadDatabase()
+	if err != nil {
+		t.Fatalf("ReadDatabase failed: %v", err)
+	}
+
+	schema := db.Schemas[0]
+
+	// Should only have 2 scripts (real_file and target), symlink should be skipped
+	if len(schema.Scripts) != 2 {
+		t.Errorf("Expected 2 scripts (symlink should be skipped), got %d", len(schema.Scripts))
+	}
+
+	// Verify the scripts are the real files, not the symlink
+	scriptNames := make(map[string]bool)
+	for _, script := range schema.Scripts {
+		scriptNames[script.Name] = true
+	}
+
+	if !scriptNames["real_file"] {
+		t.Error("Expected 'real_file' script to be present")
+	}
+	if !scriptNames["target"] {
+		t.Error("Expected 'target' script to be present")
+	}
+	if scriptNames["symlink"] {
+		t.Error("Symlink script should have been skipped but was found")
+	}
+}

pkg/writers/pgsql/NAMING_CONVENTIONS.md

@@ -0,0 +1,217 @@
+# PostgreSQL Naming Conventions
+
+Standardized naming rules for all database objects in RelSpec PostgreSQL output.
+
+## Quick Reference
+
+| Object Type       | Prefix      | Format                             | Example                  |
+| ----------------- | ----------- | ---------------------------------- | ------------------------ |
+| Primary Key       | `pk_`       | `pk_<schema>_<table>`              | `pk_public_users`        |
+| Foreign Key       | `fk_`       | `fk_<table>_<referenced_table>`    | `fk_posts_users`         |
+| Unique Constraint | `uk_`       | `uk_<table>_<column>`              | `uk_users_email`         |
+| Unique Index      | `uidx_`     | `uidx_<table>_<column>`            | `uidx_users_email`       |
+| Regular Index     | `idx_`      | `idx_<table>_<column>`             | `idx_posts_user_id`      |
+| Check Constraint  | `chk_`      | `chk_<table>_<constraint_purpose>` | `chk_users_age_positive` |
+| Sequence          | `identity_` | `identity_<table>_<column>`        | `identity_users_id`      |
+| Trigger           | `t_`        | `t_<purpose>_<table>`              | `t_audit_users`          |
+| Trigger Function  | `tf_`       | `tf_<purpose>_<table>`             | `tf_audit_users`         |
+
+## Naming Rules by Object Type
+
+### Primary Keys
+
+**Pattern:** `pk_<schema>_<table>`
+
+- Include schema name to avoid collisions across schemas
+- Use lowercase, snake_case format
+- Examples:
+  - `pk_public_users`
+  - `pk_audit_audit_log`
+  - `pk_staging_temp_data`
+
+### Foreign Keys
+
+**Pattern:** `fk_<table>_<referenced_table>`
+
+- Reference the table containing the FK followed by the referenced table
+- Use lowercase, snake_case format
+- Do NOT include column names in standard FK constraints
+- Examples:
+  - `fk_posts_users` (posts.user_id → users.id)
+  - `fk_comments_posts` (comments.post_id → posts.id)
+  - `fk_order_items_orders` (order_items.order_id → orders.id)
+
+### Unique Constraints
+
+**Pattern:** `uk_<table>_<column>`
+
+- Use `uk_` prefix strictly for database constraints (CONSTRAINT type)
+- Include column name for clarity
+- Examples:
+  - `uk_users_email`
+  - `uk_users_username`
+  - `uk_products_sku`
+
+### Unique Indexes
+
+**Pattern:** `uidx_<table>_<column>`
+
+- Use `uidx_` prefix strictly for index type objects
+- Distinguished from constraints for clarity and implementation flexibility
+- Examples:
+  - `uidx_users_email`
+  - `uidx_sessions_token`
+  - `uidx_api_keys_key`
+
+### Regular Indexes
+
+**Pattern:** `idx_<table>_<column>`
+
+- Standard indexes for query optimization
+- Single column: `idx_<table>_<column>`
+- Examples:
+  - `idx_posts_user_id`
+  - `idx_orders_created_at`
+  - `idx_users_status`
+
+### Check Constraints
+
+**Pattern:** `chk_<table>_<constraint_purpose>`
+
+- Describe the constraint validation purpose
+- Use lowercase, snake_case for the purpose
+- Examples:
+  - `chk_users_age_positive` (CHECK (age > 0))
+  - `chk_orders_quantity_positive` (CHECK (quantity > 0))
+  - `chk_products_price_valid` (CHECK (price >= 0))
+  - `chk_users_status_enum` (CHECK (status IN ('active', 'inactive')))
+
+### Sequences
+
+**Pattern:** `identity_<table>_<column>`
+
+- Used for SERIAL/IDENTITY columns
+- Explicitly named for clarity and management
+- Examples:
+  - `identity_users_id`
+  - `identity_posts_id`
+  - `identity_transactions_id`
+
+### Triggers
+
+**Pattern:** `t_<purpose>_<table>`
+
+- Include purpose before table name
+- Lowercase, snake_case format
+- Examples:
+  - `t_audit_users` (audit trigger on users table)
+  - `t_update_timestamp_posts` (timestamp update trigger on posts)
+  - `t_validate_orders` (validation trigger on orders)
+
+### Trigger Functions
+
+**Pattern:** `tf_<purpose>_<table>`
+
+- Pair with trigger naming convention
+- Use `tf_` prefix to distinguish from triggers themselves
+- Examples:
+  - `tf_audit_users` (function for t_audit_users)
+  - `tf_update_timestamp_posts` (function for t_update_timestamp_posts)
+  - `tf_validate_orders` (function for t_validate_orders)
+
+## Multi-Column Objects
+
+### Composite Primary Keys
+
+**Pattern:** `pk_<schema>_<table>`
+
+- Same as single-column PKs
+- Example: `pk_public_order_items` (composite key on order_id + item_id)
+
+### Composite Unique Constraints
+
+**Pattern:** `uk_<table>_<column1>_<column2>_[...]`
+
+- Append all column names in order
+- Examples:
+  - `uk_users_email_domain` (UNIQUE(email, domain))
+  - `uk_inventory_warehouse_sku` (UNIQUE(warehouse_id, sku))
+
+### Composite Unique Indexes
+
+**Pattern:** `uidx_<table>_<column1>_<column2>_[...]`
+
+- Append all column names in order
+- Examples:
+  - `uidx_users_first_name_last_name` (UNIQUE INDEX on first_name, last_name)
+  - `uidx_sessions_user_id_device_id` (UNIQUE INDEX on user_id, device_id)
+
+### Composite Regular Indexes
+
+**Pattern:** `idx_<table>_<column1>_<column2>_[...]`
+
+- Append all column names in order
+- List columns in typical query filter order
+- Examples:
+  - `idx_orders_user_id_created_at` (filter by user, then sort by created_at)
+  - `idx_logs_level_timestamp` (filter by level, then by timestamp)
+
+## Special Cases & Conventions
+
+### Audit Trail Tables
+
+- Audit table naming: `<original_table>_audit` or `audit_<original_table>`
+- Audit indexes follow standard pattern: `idx_<audit_table>_<column>`
+- Examples:
+  - Users table audit: `users_audit` with `idx_users_audit_tablename`, `idx_users_audit_changedate`
+  - Posts table audit: `posts_audit` with `idx_posts_audit_tablename`, `idx_posts_audit_changedate`
+
+### Temporal/Versioning Tables
+
+- Use suffix `_history` or `_versions` if needed
+- Apply standard naming rules with the full table name
+- Examples:
+  - `idx_users_history_user_id`
+  - `uk_posts_versions_version_number`
+
+### Schema-Specific Objects
+
+- Always qualify with schema when needed: `pk_<schema>_<table>`
+- Multiple schemas allowed: `pk_public_users`, `pk_staging_users`
+
+### Reserved Words & Special Names
+
+- Avoid PostgreSQL reserved keywords in object names
+- If column/table names conflict, use quoted identifiers in DDL
+- Naming convention rules still apply to the logical name
+
+### Generated/Anonymous Indexes
+
+- If an index lacks explicit naming, default to: `idx_<schema>_<table>`
+- Should be replaced with explicit names following standards
+- Examples (to be renamed):
+  - `idx_public_users` → should be `idx_users_<column>`
+
+## Implementation Notes
+
+### Code Generation
+
+- Names are always lowercase in generated SQL
+- Underscore separators are required
+
+### Migration Safety
+
+- Do NOT rename objects after creation without explicit migration
+- Names should be consistent across all schema versions
+- Test generated DDL against PostgreSQL before deployment
+
+### Testing
+
+- Ensure consistency across all table and constraint generation
+- Test with reserved words to verify escaping
+
+## Related Documentation
+
+- PostgreSQL Identifier Rules: https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-IDENTIFIERS
+- Constraint Documentation: https://www.postgresql.org/docs/current/ddl-constraints.html
+- Index Documentation: https://www.postgresql.org/docs/current/indexes.html

pkg/writers/pgsql/migration_writer.go

@@ -477,7 +477,7 @@ func (w *MigrationWriter) generateIndexScripts(model *models.Schema, current *mo
 			}
 			if len(pkColumns) > 0 {
 				sort.Strings(pkColumns)
-				constraintName := fmt.Sprintf("pk_%s_%s", strings.ToLower(model.Name), strings.ToLower(modelTable.Name))
+				constraintName := fmt.Sprintf("pk_%s_%s", model.SQLName(), modelTable.SQLName())
 				shouldCreate := true
 
 				if currentTable != nil {
@@ -753,7 +753,7 @@ func (w *MigrationWriter) generateAuditScripts(schema *models.Schema, auditConfi
 		}
 
 		// Generate audit function
-		funcName := fmt.Sprintf("ft_audit_%s", table.Name)
+		funcName := fmt.Sprintf("tf_audit_%s", table.Name)
 		funcData := BuildAuditFunctionData(schema.Name, table, pk, config, auditSchema, auditConfig.UserFunction)
 
 		funcSQL, err := w.executor.ExecuteAuditFunction(funcData)

pkg/writers/pgsql/migration_writer_test.go

@@ -121,7 +121,7 @@ func TestWriteMigration_WithAudit(t *testing.T) {
 	}
 
 	// Verify audit function
-	if !strings.Contains(output, "CREATE OR REPLACE FUNCTION public.ft_audit_users()") {
+	if !strings.Contains(output, "CREATE OR REPLACE FUNCTION public.tf_audit_users()") {
 		t.Error("Migration missing audit function")
 	}
 
@@ -177,7 +177,7 @@ func TestTemplateExecutor_AuditFunction(t *testing.T) {
 
 	data := AuditFunctionData{
 		SchemaName:      "public",
-		FunctionName:    "ft_audit_users",
+		FunctionName:    "tf_audit_users",
 		TableName:       "users",
 		TablePrefix:     "NULL",
 		PrimaryKey:      "id",
@@ -202,7 +202,7 @@ func TestTemplateExecutor_AuditFunction(t *testing.T) {
 
 	t.Logf("Generated SQL:\n%s", sql)
 
-	if !strings.Contains(sql, "CREATE OR REPLACE FUNCTION public.ft_audit_users()") {
+	if !strings.Contains(sql, "CREATE OR REPLACE FUNCTION public.tf_audit_users()") {
 		t.Error("SQL missing function definition")
 	}
 	if !strings.Contains(sql, "IF TG_OP = 'INSERT'") {

pkg/writers/pgsql/templates.go

@@ -355,7 +355,7 @@ func BuildAuditFunctionData(
 	auditSchema string,
 	userFunction string,
 ) AuditFunctionData {
-	funcName := fmt.Sprintf("ft_audit_%s", table.Name)
+	funcName := fmt.Sprintf("tf_audit_%s", table.Name)
 
 	// Build list of audited columns
 	auditedColumns := make([]*models.Column, 0)

pkg/writers/pgsql/writer.go

@@ -168,6 +168,13 @@ func (w *Writer) GenerateSchemaStatements(schema *models.Schema) ([]string, erro
 		statements = append(statements, stmts...)
 	}
 
+	// Phase 3.5: Add missing columns (for existing tables)
+	addColStmts, err := w.GenerateAddColumnStatements(schema)
+	if err != nil {
+		return nil, fmt.Errorf("failed to generate add column statements: %w", err)
+	}
+	statements = append(statements, addColStmts...)
+
 	// Phase 4: Primary keys
 	for _, table := range schema.Tables {
 		// First check for explicit PrimaryKeyConstraint
@@ -179,27 +186,67 @@ func (w *Writer) GenerateSchemaStatements(schema *models.Schema) ([]string, erro
 			}
 		}
 
+		var pkColumns []string
+		var pkName string
+
 		if pkConstraint != nil {
-			stmt := fmt.Sprintf("ALTER TABLE %s.%s ADD CONSTRAINT %s PRIMARY KEY (%s)",
+			pkColumns = pkConstraint.Columns
-				schema.SQLName(), table.SQLName(), pkConstraint.Name, strings.Join(pkConstraint.Columns, ", "))
+			pkName = pkConstraint.Name
-			statements = append(statements, stmt)
 		} else {
 			// No explicit constraint, check for columns with IsPrimaryKey = true
-			pkColumns := []string{}
+			pkCols := []string{}
 			for _, col := range table.Columns {
 				if col.IsPrimaryKey {
-					pkColumns = append(pkColumns, col.SQLName())
+					pkCols = append(pkCols, col.SQLName())
 				}
 			}
-			if len(pkColumns) > 0 {
+			if len(pkCols) > 0 {
 				// Sort for consistent output
-				sort.Strings(pkColumns)
+				sort.Strings(pkCols)
-				pkName := fmt.Sprintf("pk_%s_%s", schema.SQLName(), table.SQLName())
+				pkColumns = pkCols
-				stmt := fmt.Sprintf("ALTER TABLE %s.%s ADD CONSTRAINT %s PRIMARY KEY (%s)",
+				pkName = fmt.Sprintf("pk_%s_%s", schema.SQLName(), table.SQLName())
-					schema.SQLName(), table.SQLName(), pkName, strings.Join(pkColumns, ", "))
-				statements = append(statements, stmt)
 			}
 		}
+
+		if len(pkColumns) > 0 {
+			// Auto-generated primary key names to check for and drop
+			autoGenPKNames := []string{
+				fmt.Sprintf("%s_pkey", table.Name),
+				fmt.Sprintf("%s_%s_pkey", schema.Name, table.Name),
+			}
+
+			// Wrap in DO block to drop auto-generated PK and add our named PK
+			stmt := fmt.Sprintf("DO $$\nDECLARE\n"+
+				"  auto_pk_name text;\n"+
+				"BEGIN\n"+
+				"  -- Drop auto-generated primary key if it exists\n"+
+				"  SELECT constraint_name INTO auto_pk_name\n"+
+				"  FROM information_schema.table_constraints\n"+
+				"  WHERE table_schema = '%s'\n"+
+				"    AND table_name = '%s'\n"+
+				"    AND constraint_type = 'PRIMARY KEY'\n"+
+				"    AND constraint_name IN (%s);\n"+
+				"\n"+
+				"  IF auto_pk_name IS NOT NULL THEN\n"+
+				"    EXECUTE 'ALTER TABLE %s.%s DROP CONSTRAINT ' || quote_ident(auto_pk_name);\n"+
+				"  END IF;\n"+
+				"\n"+
+				"  -- Add named primary key if it doesn't exist\n"+
+				"  IF NOT EXISTS (\n"+
+				"    SELECT 1 FROM information_schema.table_constraints\n"+
+				"    WHERE table_schema = '%s'\n"+
+				"      AND table_name = '%s'\n"+
+				"      AND constraint_name = '%s'\n"+
+				"  ) THEN\n"+
+				"    ALTER TABLE %s.%s ADD CONSTRAINT %s PRIMARY KEY (%s);\n"+
+				"  END IF;\n"+
+				"END;\n$$",
+				schema.Name, table.Name, formatStringList(autoGenPKNames),
+				schema.SQLName(), table.SQLName(),
+				schema.Name, table.Name, pkName,
+				schema.SQLName(), table.SQLName(), pkName, strings.Join(pkColumns, ", "))
+			statements = append(statements, stmt)
+		}
 	}
 
 	// Phase 5: Indexes
@@ -270,7 +317,18 @@ func (w *Writer) GenerateSchemaStatements(schema *models.Schema) ([]string, erro
 				onUpdate = "NO ACTION"
 			}
 
-			stmt := fmt.Sprintf("ALTER TABLE %s.%s ADD CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s.%s(%s) ON DELETE %s ON UPDATE %s",
+			// Wrap in DO block to check for existing constraint
+			stmt := fmt.Sprintf("DO $$\nBEGIN\n"+
+				"  IF NOT EXISTS (\n"+
+				"    SELECT 1 FROM information_schema.table_constraints\n"+
+				"    WHERE table_schema = '%s'\n"+
+				"      AND table_name = '%s'\n"+
+				"      AND constraint_name = '%s'\n"+
+				"  ) THEN\n"+
+				"    ALTER TABLE %s.%s ADD CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s.%s(%s) ON DELETE %s ON UPDATE %s;\n"+
+				"  END IF;\n"+
+				"END;\n$$",
+				schema.Name, table.Name, constraint.Name,
 				schema.SQLName(), table.SQLName(), constraint.Name,
 				strings.Join(constraint.Columns, ", "),
 				strings.ToLower(refSchema), strings.ToLower(constraint.ReferencedTable),
@@ -300,6 +358,68 @@ func (w *Writer) GenerateSchemaStatements(schema *models.Schema) ([]string, erro
 	return statements, nil
 }
 
+// GenerateAddColumnStatements generates ALTER TABLE ADD COLUMN statements for existing tables
+// This is useful for schema evolution when new columns are added to existing tables
+func (w *Writer) GenerateAddColumnStatements(schema *models.Schema) ([]string, error) {
+	statements := []string{}
+
+	statements = append(statements, fmt.Sprintf("-- Add missing columns for schema: %s", schema.Name))
+
+	for _, table := range schema.Tables {
+		// Sort columns by sequence or name for consistent output
+		columns := make([]*models.Column, 0, len(table.Columns))
+		for _, col := range table.Columns {
+			columns = append(columns, col)
+		}
+		sort.Slice(columns, func(i, j int) bool {
+			if columns[i].Sequence != columns[j].Sequence {
+				return columns[i].Sequence < columns[j].Sequence
+			}
+			return columns[i].Name < columns[j].Name
+		})
+
+		for _, col := range columns {
+			colDef := w.generateColumnDefinition(col)
+
+			// Generate DO block that checks if column exists before adding
+			stmt := fmt.Sprintf("DO $$\nBEGIN\n"+
+				"  IF NOT EXISTS (\n"+
+				"    SELECT 1 FROM information_schema.columns\n"+
+				"    WHERE table_schema = '%s'\n"+
+				"      AND table_name = '%s'\n"+
+				"      AND column_name = '%s'\n"+
+				"  ) THEN\n"+
+				"    ALTER TABLE %s.%s ADD COLUMN %s;\n"+
+				"  END IF;\n"+
+				"END;\n$$",
+				schema.Name, table.Name, col.Name,
+				schema.SQLName(), table.SQLName(), colDef)
+			statements = append(statements, stmt)
+		}
+	}
+
+	return statements, nil
+}
+
+// GenerateAddColumnsForDatabase generates ALTER TABLE ADD COLUMN statements for the entire database
+func (w *Writer) GenerateAddColumnsForDatabase(db *models.Database) ([]string, error) {
+	statements := []string{}
+
+	statements = append(statements, "-- Add missing columns to existing tables")
+	statements = append(statements, fmt.Sprintf("-- Database: %s", db.Name))
+	statements = append(statements, "-- Generated by RelSpec")
+
+	for _, schema := range db.Schemas {
+		schemaStatements, err := w.GenerateAddColumnStatements(schema)
+		if err != nil {
+			return nil, fmt.Errorf("failed to generate add column statements for schema %s: %w", schema.Name, err)
+		}
+		statements = append(statements, schemaStatements...)
+	}
+
+	return statements, nil
+}
+
 // generateCreateTableStatement generates CREATE TABLE statement
 func (w *Writer) generateCreateTableStatement(schema *models.Schema, table *models.Table) ([]string, error) {
 	statements := []string{}
@@ -322,7 +442,7 @@ func (w *Writer) generateCreateTableStatement(schema *models.Schema, table *mode
 		columnDefs = append(columnDefs, "  "+def)
 	}
 
-	stmt := fmt.Sprintf("CREATE TABLE %s.%s (\n%s\n)",
+	stmt := fmt.Sprintf("CREATE TABLE IF NOT EXISTS %s.%s (\n%s\n)",
 		schema.SQLName(), table.SQLName(), strings.Join(columnDefs, ",\n"))
 	statements = append(statements, stmt)
 
@@ -336,14 +456,25 @@ func (w *Writer) generateColumnDefinition(col *models.Column) string {
 	// Type with length/precision - convert to valid PostgreSQL type
 	baseType := pgsql.ConvertSQLType(col.Type)
 	typeStr := baseType
+
+	// Only add size specifiers for types that support them
 	if col.Length > 0 && col.Precision == 0 {
-		typeStr = fmt.Sprintf("%s(%d)", baseType, col.Length)
+		if supportsLength(baseType) {
-	} else if col.Precision > 0 {
+			typeStr = fmt.Sprintf("%s(%d)", baseType, col.Length)
-		if col.Scale > 0 {
+		} else if isTextTypeWithoutLength(baseType) {
-			typeStr = fmt.Sprintf("%s(%d,%d)", baseType, col.Precision, col.Scale)
+			// Convert text with length to varchar
-		} else {
+			typeStr = fmt.Sprintf("varchar(%d)", col.Length)
-			typeStr = fmt.Sprintf("%s(%d)", baseType, col.Precision)
 		}
+		// For types that don't support length (integer, bigint, etc.), ignore the length
+	} else if col.Precision > 0 {
+		if supportsPrecision(baseType) {
+			if col.Scale > 0 {
+				typeStr = fmt.Sprintf("%s(%d,%d)", baseType, col.Precision, col.Scale)
+			} else {
+				typeStr = fmt.Sprintf("%s(%d)", baseType, col.Precision)
+			}
+		}
+		// For types that don't support precision, ignore it
 	}
 	parts = append(parts, typeStr)
 
@@ -396,6 +527,11 @@ func (w *Writer) WriteSchema(schema *models.Schema) error {
 		return err
 	}
 
+	// Phase 3.5: Add missing columns (priority 120)
+	if err := w.writeAddColumns(schema); err != nil {
+		return err
+	}
+
 	// Phase 4: Create primary keys (priority 160)
 	if err := w.writePrimaryKeys(schema); err != nil {
 		return err
@@ -437,6 +573,44 @@ func (w *Writer) WriteTable(table *models.Table) error {
 	return w.WriteSchema(schema)
 }
 
+// WriteAddColumnStatements writes ALTER TABLE ADD COLUMN statements for a database
+// This is used for schema evolution/migration when new columns are added
+func (w *Writer) WriteAddColumnStatements(db *models.Database) error {
+	var writer io.Writer
+	var file *os.File
+	var err error
+
+	// Use existing writer if already set (for testing)
+	if w.writer != nil {
+		writer = w.writer
+	} else if w.options.OutputPath != "" {
+		// Determine output destination
+		file, err = os.Create(w.options.OutputPath)
+		if err != nil {
+			return fmt.Errorf("failed to create output file: %w", err)
+		}
+		defer file.Close()
+		writer = file
+	} else {
+		writer = os.Stdout
+	}
+
+	w.writer = writer
+
+	// Generate statements
+	statements, err := w.GenerateAddColumnsForDatabase(db)
+	if err != nil {
+		return err
+	}
+
+	// Write each statement
+	for _, stmt := range statements {
+		fmt.Fprintf(w.writer, "%s;\n\n", stmt)
+	}
+
+	return nil
+}
+
 // writeCreateSchema generates CREATE SCHEMA statement
 func (w *Writer) writeCreateSchema(schema *models.Schema) error {
 	if schema.Name == "public" {
@@ -490,15 +664,8 @@ func (w *Writer) writeCreateTables(schema *models.Schema) error {
 		columnDefs := make([]string, 0, len(columns))
 
 		for _, col := range columns {
-			colDef := fmt.Sprintf("  %s %s", col.SQLName(), pgsql.ConvertSQLType(col.Type))
+			// Use generateColumnDefinition to properly handle type, length, precision, and defaults
-
+			colDef := "  " + w.generateColumnDefinition(col)
-			// Add default value if present
-			if col.Default != nil && col.Default != "" {
-				// Strip backticks - DBML uses them for SQL expressions but PostgreSQL doesn't
-				defaultVal := fmt.Sprintf("%v", col.Default)
-				colDef += fmt.Sprintf(" DEFAULT %s", stripBackticks(defaultVal))
-			}
-
 			columnDefs = append(columnDefs, colDef)
 		}
 
@@ -509,6 +676,35 @@ func (w *Writer) writeCreateTables(schema *models.Schema) error {
 	return nil
 }
 
+// writeAddColumns generates ALTER TABLE ADD COLUMN statements for missing columns
+func (w *Writer) writeAddColumns(schema *models.Schema) error {
+	fmt.Fprintf(w.writer, "-- Add missing columns for schema: %s\n", schema.Name)
+
+	for _, table := range schema.Tables {
+		// Sort columns by sequence or name for consistent output
+		columns := getSortedColumns(table.Columns)
+
+		for _, col := range columns {
+			colDef := w.generateColumnDefinition(col)
+
+			// Generate DO block that checks if column exists before adding
+			fmt.Fprintf(w.writer, "DO $$\nBEGIN\n")
+			fmt.Fprintf(w.writer, "  IF NOT EXISTS (\n")
+			fmt.Fprintf(w.writer, "    SELECT 1 FROM information_schema.columns\n")
+			fmt.Fprintf(w.writer, "    WHERE table_schema = '%s'\n", schema.Name)
+			fmt.Fprintf(w.writer, "      AND table_name = '%s'\n", table.Name)
+			fmt.Fprintf(w.writer, "      AND column_name = '%s'\n", col.Name)
+			fmt.Fprintf(w.writer, "  ) THEN\n")
+			fmt.Fprintf(w.writer, "    ALTER TABLE %s.%s ADD COLUMN %s;\n",
+				schema.SQLName(), table.SQLName(), colDef)
+			fmt.Fprintf(w.writer, "  END IF;\n")
+			fmt.Fprintf(w.writer, "END;\n$$;\n\n")
+		}
+	}
+
+	return nil
+}
+
 // writePrimaryKeys generates ALTER TABLE statements for primary keys
 func (w *Writer) writePrimaryKeys(schema *models.Schema) error {
 	fmt.Fprintf(w.writer, "-- Primary keys for schema: %s\n", schema.Name)
@@ -550,7 +746,32 @@ func (w *Writer) writePrimaryKeys(schema *models.Schema) error {
 			continue
 		}
 
-		fmt.Fprintf(w.writer, "DO $$\nBEGIN\n")
+		// Auto-generated primary key names to check for and drop
+		autoGenPKNames := []string{
+			fmt.Sprintf("%s_pkey", table.Name),
+			fmt.Sprintf("%s_%s_pkey", schema.Name, table.Name),
+		}
+
+		fmt.Fprintf(w.writer, "DO $$\nDECLARE\n")
+		fmt.Fprintf(w.writer, "  auto_pk_name text;\nBEGIN\n")
+
+		// Check for and drop auto-generated primary keys
+		fmt.Fprintf(w.writer, "  -- Drop auto-generated primary key if it exists\n")
+		fmt.Fprintf(w.writer, "  SELECT constraint_name INTO auto_pk_name\n")
+		fmt.Fprintf(w.writer, "  FROM information_schema.table_constraints\n")
+		fmt.Fprintf(w.writer, "  WHERE table_schema = '%s'\n", schema.Name)
+		fmt.Fprintf(w.writer, "    AND table_name = '%s'\n", table.Name)
+		fmt.Fprintf(w.writer, "    AND constraint_type = 'PRIMARY KEY'\n")
+		fmt.Fprintf(w.writer, "    AND constraint_name IN (%s);\n", formatStringList(autoGenPKNames))
+		fmt.Fprintf(w.writer, "\n")
+		fmt.Fprintf(w.writer, "  IF auto_pk_name IS NOT NULL THEN\n")
+		fmt.Fprintf(w.writer, "    EXECUTE 'ALTER TABLE %s.%s DROP CONSTRAINT ' || quote_ident(auto_pk_name);\n",
+			schema.SQLName(), table.SQLName())
+		fmt.Fprintf(w.writer, "  END IF;\n")
+		fmt.Fprintf(w.writer, "\n")
+
+		// Add our named primary key if it doesn't exist
+		fmt.Fprintf(w.writer, "  -- Add named primary key if it doesn't exist\n")
 		fmt.Fprintf(w.writer, "  IF NOT EXISTS (\n")
 		fmt.Fprintf(w.writer, "    SELECT 1 FROM information_schema.table_constraints\n")
 		fmt.Fprintf(w.writer, "    WHERE table_schema = '%s'\n", schema.Name)
@@ -592,9 +813,10 @@ func (w *Writer) writeIndexes(schema *models.Schema) error {
 			if indexName == "" {
 				indexType := "idx"
 				if index.Unique {
-					indexType = "uk"
+					indexType = "uidx"
 				}
-				indexName = fmt.Sprintf("%s_%s_%s", indexType, schema.SQLName(), table.SQLName())
+				columnSuffix := strings.Join(index.Columns, "_")
+				indexName = fmt.Sprintf("%s_%s_%s", indexType, table.SQLName(), strings.ToLower(columnSuffix))
 			}
 
 			// Build column list with operator class support for GIN indexes
@@ -710,13 +932,6 @@ func (w *Writer) writeForeignKeys(schema *models.Schema) error {
 				onUpdate = strings.ToUpper(fkConstraint.OnUpdate)
 			}
 
-			fmt.Fprintf(w.writer, "ALTER TABLE %s.%s\n", schema.SQLName(), table.SQLName())
-			fmt.Fprintf(w.writer, "  DROP CONSTRAINT IF EXISTS %s;\n", fkName)
-			fmt.Fprintf(w.writer, "\n")
-			fmt.Fprintf(w.writer, "ALTER TABLE %s.%s\n", schema.SQLName(), table.SQLName())
-			fmt.Fprintf(w.writer, "  ADD CONSTRAINT %s\n", fkName)
-			fmt.Fprintf(w.writer, "  FOREIGN KEY (%s)\n", strings.Join(sourceColumns, ", "))
-
 			// Use constraint's referenced schema/table or relationship's ToSchema/ToTable
 			refSchema := fkConstraint.ReferencedSchema
 			if refSchema == "" {
@@ -727,11 +942,24 @@ func (w *Writer) writeForeignKeys(schema *models.Schema) error {
 				refTable = rel.ToTable
 			}
 
-			fmt.Fprintf(w.writer, "  REFERENCES %s.%s (%s)\n",
+			// Use DO block to check if constraint exists before adding
+			fmt.Fprintf(w.writer, "DO $$\nBEGIN\n")
+			fmt.Fprintf(w.writer, "  IF NOT EXISTS (\n")
+			fmt.Fprintf(w.writer, "    SELECT 1 FROM information_schema.table_constraints\n")
+			fmt.Fprintf(w.writer, "    WHERE table_schema = '%s'\n", schema.Name)
+			fmt.Fprintf(w.writer, "      AND table_name = '%s'\n", table.Name)
+			fmt.Fprintf(w.writer, "      AND constraint_name = '%s'\n", fkName)
+			fmt.Fprintf(w.writer, "  ) THEN\n")
+			fmt.Fprintf(w.writer, "    ALTER TABLE %s.%s\n", schema.SQLName(), table.SQLName())
+			fmt.Fprintf(w.writer, "      ADD CONSTRAINT %s\n", fkName)
+			fmt.Fprintf(w.writer, "      FOREIGN KEY (%s)\n", strings.Join(sourceColumns, ", "))
+			fmt.Fprintf(w.writer, "      REFERENCES %s.%s (%s)\n",
 				refSchema, refTable, strings.Join(targetColumns, ", "))
-			fmt.Fprintf(w.writer, "  ON DELETE %s\n", onDelete)
+			fmt.Fprintf(w.writer, "      ON DELETE %s\n", onDelete)
-			fmt.Fprintf(w.writer, "  ON UPDATE %s\n", onUpdate)
+			fmt.Fprintf(w.writer, "      ON UPDATE %s\n", onUpdate)
-			fmt.Fprintf(w.writer, "  DEFERRABLE;\n\n")
+			fmt.Fprintf(w.writer, "      DEFERRABLE;\n")
+			fmt.Fprintf(w.writer, "  END IF;\n")
+			fmt.Fprintf(w.writer, "END;\n$$;\n\n")
 		}
 	}
 
@@ -843,6 +1071,44 @@ func isTextType(colType string) bool {
 	return false
 }
 
+// supportsLength checks if a PostgreSQL type supports length specification
+func supportsLength(colType string) bool {
+	lengthTypes := []string{"varchar", "character varying", "char", "character", "bit", "bit varying", "varbit"}
+	lowerType := strings.ToLower(colType)
+	for _, t := range lengthTypes {
+		if lowerType == t || strings.HasPrefix(lowerType, t+"(") {
+			return true
+		}
+	}
+	return false
+}
+
+// supportsPrecision checks if a PostgreSQL type supports precision/scale specification
+func supportsPrecision(colType string) bool {
+	precisionTypes := []string{"numeric", "decimal", "time", "timestamp", "timestamptz", "timestamp with time zone", "timestamp without time zone", "time with time zone", "time without time zone", "interval"}
+	lowerType := strings.ToLower(colType)
+	for _, t := range precisionTypes {
+		if lowerType == t || strings.HasPrefix(lowerType, t+"(") {
+			return true
+		}
+	}
+	return false
+}
+
+// isTextTypeWithoutLength checks if type is text (which should convert to varchar when length is specified)
+func isTextTypeWithoutLength(colType string) bool {
+	return strings.EqualFold(colType, "text")
+}
+
+// formatStringList formats a list of strings as a SQL-safe comma-separated quoted list
+func formatStringList(items []string) string {
+	quoted := make([]string, len(items))
+	for i, item := range items {
+		quoted[i] = fmt.Sprintf("'%s'", escapeQuote(item))
+	}
+	return strings.Join(quoted, ", ")
+}
+
 // extractOperatorClass extracts operator class from index comment/note
 // Looks for common operator classes like gin_trgm_ops, gist_trgm_ops, etc.
 func extractOperatorClass(comment string) string {

pkg/writers/pgsql/writer_test.go

@@ -45,11 +45,11 @@ func TestWriteDatabase(t *testing.T) {
 
 	// Add unique index
 	uniqueEmailIndex := &models.Index{
-		Name:    "uk_users_email",
+		Name:    "uidx_users_email",
 		Unique:  true,
 		Columns: []string{"email"},
 	}
-	table.Indexes["uk_users_email"] = uniqueEmailIndex
+	table.Indexes["uidx_users_email"] = uniqueEmailIndex
 
 	schema.Tables = append(schema.Tables, table)
 	db.Schemas = append(db.Schemas, schema)
@@ -305,3 +305,263 @@ func TestTypeConversion(t *testing.T) {
 		t.Errorf("Output missing 'smallint' type (converted from 'int16')\nFull output:\n%s", output)
 	}
 }
+
+func TestPrimaryKeyExistenceCheck(t *testing.T) {
+	db := models.InitDatabase("testdb")
+	schema := models.InitSchema("public")
+	table := models.InitTable("products", "public")
+
+	idCol := models.InitColumn("id", "products", "public")
+	idCol.Type = "integer"
+	idCol.IsPrimaryKey = true
+	table.Columns["id"] = idCol
+
+	nameCol := models.InitColumn("name", "products", "public")
+	nameCol.Type = "text"
+	table.Columns["name"] = nameCol
+
+	schema.Tables = append(schema.Tables, table)
+	db.Schemas = append(db.Schemas, schema)
+
+	var buf bytes.Buffer
+	options := &writers.WriterOptions{}
+	writer := NewWriter(options)
+	writer.writer = &buf
+
+	err := writer.WriteDatabase(db)
+	if err != nil {
+		t.Fatalf("WriteDatabase failed: %v", err)
+	}
+
+	output := buf.String()
+	t.Logf("Generated SQL:\n%s", output)
+
+	// Verify our naming convention is used
+	if !strings.Contains(output, "pk_public_products") {
+		t.Errorf("Output missing expected primary key name 'pk_public_products'\nFull output:\n%s", output)
+	}
+
+	// Verify it drops auto-generated primary keys
+	if !strings.Contains(output, "products_pkey") || !strings.Contains(output, "DROP CONSTRAINT") {
+		t.Errorf("Output missing logic to drop auto-generated primary key\nFull output:\n%s", output)
+	}
+
+	// Verify it checks for our specific named constraint before adding it
+	if !strings.Contains(output, "constraint_name = 'pk_public_products'") {
+		t.Errorf("Output missing check for our named primary key constraint\nFull output:\n%s", output)
+	}
+}
+
+func TestColumnSizeSpecifiers(t *testing.T) {
+	db := models.InitDatabase("testdb")
+	schema := models.InitSchema("public")
+	table := models.InitTable("test_sizes", "public")
+
+	// Integer with invalid size specifier - should ignore size
+	integerCol := models.InitColumn("int_col", "test_sizes", "public")
+	integerCol.Type = "integer"
+	integerCol.Length = 32
+	table.Columns["int_col"] = integerCol
+
+	// Bigint with invalid size specifier - should ignore size
+	bigintCol := models.InitColumn("bigint_col", "test_sizes", "public")
+	bigintCol.Type = "bigint"
+	bigintCol.Length = 64
+	table.Columns["bigint_col"] = bigintCol
+
+	// Smallint with invalid size specifier - should ignore size
+	smallintCol := models.InitColumn("smallint_col", "test_sizes", "public")
+	smallintCol.Type = "smallint"
+	smallintCol.Length = 16
+	table.Columns["smallint_col"] = smallintCol
+
+	// Text with length - should convert to varchar
+	textCol := models.InitColumn("text_col", "test_sizes", "public")
+	textCol.Type = "text"
+	textCol.Length = 100
+	table.Columns["text_col"] = textCol
+
+	// Varchar with length - should keep varchar with length
+	varcharCol := models.InitColumn("varchar_col", "test_sizes", "public")
+	varcharCol.Type = "varchar"
+	varcharCol.Length = 50
+	table.Columns["varchar_col"] = varcharCol
+
+	// Decimal with precision and scale - should keep them
+	decimalCol := models.InitColumn("decimal_col", "test_sizes", "public")
+	decimalCol.Type = "decimal"
+	decimalCol.Precision = 19
+	decimalCol.Scale = 4
+	table.Columns["decimal_col"] = decimalCol
+
+	schema.Tables = append(schema.Tables, table)
+	db.Schemas = append(db.Schemas, schema)
+
+	var buf bytes.Buffer
+	options := &writers.WriterOptions{}
+	writer := NewWriter(options)
+	writer.writer = &buf
+
+	err := writer.WriteDatabase(db)
+	if err != nil {
+		t.Fatalf("WriteDatabase failed: %v", err)
+	}
+
+	output := buf.String()
+	t.Logf("Generated SQL:\n%s", output)
+
+	// Verify invalid size specifiers are NOT present
+	invalidPatterns := []string{
+		"integer(32)",
+		"bigint(64)",
+		"smallint(16)",
+		"text(100)",
+	}
+	for _, pattern := range invalidPatterns {
+		if strings.Contains(output, pattern) {
+			t.Errorf("Output contains invalid pattern '%s' - PostgreSQL doesn't support this\nFull output:\n%s", pattern, output)
+		}
+	}
+
+	// Verify valid patterns ARE present
+	validPatterns := []string{
+		"integer",     // without size
+		"bigint",      // without size
+		"smallint",    // without size
+		"varchar(100)", // text converted to varchar with length
+		"varchar(50)",  // varchar with length
+		"decimal(19,4)", // decimal with precision and scale
+	}
+	for _, pattern := range validPatterns {
+		if !strings.Contains(output, pattern) {
+			t.Errorf("Output missing expected pattern '%s'\nFull output:\n%s", pattern, output)
+		}
+	}
+}
+
+func TestGenerateAddColumnStatements(t *testing.T) {
+	// Create a test database with tables that have new columns
+	db := models.InitDatabase("testdb")
+	schema := models.InitSchema("public")
+
+	// Create a table with columns
+	table := models.InitTable("users", "public")
+
+	// Existing column
+	idCol := models.InitColumn("id", "users", "public")
+	idCol.Type = "integer"
+	idCol.NotNull = true
+	idCol.Sequence = 1
+	table.Columns["id"] = idCol
+
+	// New column to be added
+	emailCol := models.InitColumn("email", "users", "public")
+	emailCol.Type = "varchar"
+	emailCol.Length = 255
+	emailCol.NotNull = true
+	emailCol.Sequence = 2
+	table.Columns["email"] = emailCol
+
+	// New column with default
+	statusCol := models.InitColumn("status", "users", "public")
+	statusCol.Type = "text"
+	statusCol.Default = "active"
+	statusCol.Sequence = 3
+	table.Columns["status"] = statusCol
+
+	schema.Tables = append(schema.Tables, table)
+	db.Schemas = append(db.Schemas, schema)
+
+	// Create writer
+	options := &writers.WriterOptions{}
+	writer := NewWriter(options)
+
+	// Generate ADD COLUMN statements
+	statements, err := writer.GenerateAddColumnsForDatabase(db)
+	if err != nil {
+		t.Fatalf("GenerateAddColumnsForDatabase failed: %v", err)
+	}
+
+	// Join all statements to verify content
+	output := strings.Join(statements, "\n")
+	t.Logf("Generated ADD COLUMN statements:\n%s", output)
+
+	// Verify expected elements
+	expectedStrings := []string{
+		"ALTER TABLE public.users ADD COLUMN id integer NOT NULL",
+		"ALTER TABLE public.users ADD COLUMN email varchar(255) NOT NULL",
+		"ALTER TABLE public.users ADD COLUMN status text DEFAULT 'active'",
+		"information_schema.columns",
+		"table_schema = 'public'",
+		"table_name = 'users'",
+		"column_name = 'id'",
+		"column_name = 'email'",
+		"column_name = 'status'",
+	}
+
+	for _, expected := range expectedStrings {
+		if !strings.Contains(output, expected) {
+			t.Errorf("Output missing expected string: %s\nFull output:\n%s", expected, output)
+		}
+	}
+
+	// Verify DO blocks are present for conditional adds
+	doBlockCount := strings.Count(output, "DO $$")
+	if doBlockCount < 3 {
+		t.Errorf("Expected at least 3 DO blocks (one per column), got %d", doBlockCount)
+	}
+
+	// Verify IF NOT EXISTS logic
+	ifNotExistsCount := strings.Count(output, "IF NOT EXISTS")
+	if ifNotExistsCount < 3 {
+		t.Errorf("Expected at least 3 IF NOT EXISTS checks (one per column), got %d", ifNotExistsCount)
+	}
+}
+
+func TestWriteAddColumnStatements(t *testing.T) {
+	// Create a test database
+	db := models.InitDatabase("testdb")
+	schema := models.InitSchema("public")
+
+	// Create a table with a new column to be added
+	table := models.InitTable("products", "public")
+
+	idCol := models.InitColumn("id", "products", "public")
+	idCol.Type = "integer"
+	table.Columns["id"] = idCol
+
+	// New column with various properties
+	descCol := models.InitColumn("description", "products", "public")
+	descCol.Type = "text"
+	descCol.NotNull = false
+	table.Columns["description"] = descCol
+
+	schema.Tables = append(schema.Tables, table)
+	db.Schemas = append(db.Schemas, schema)
+
+	// Create writer with output to buffer
+	var buf bytes.Buffer
+	options := &writers.WriterOptions{}
+	writer := NewWriter(options)
+	writer.writer = &buf
+
+	// Write ADD COLUMN statements
+	err := writer.WriteAddColumnStatements(db)
+	if err != nil {
+		t.Fatalf("WriteAddColumnStatements failed: %v", err)
+	}
+
+	output := buf.String()
+	t.Logf("Generated output:\n%s", output)
+
+	// Verify output contains expected elements
+	if !strings.Contains(output, "ALTER TABLE public.products ADD COLUMN id integer") {
+		t.Errorf("Output missing ADD COLUMN for id\nFull output:\n%s", output)
+	}
+	if !strings.Contains(output, "ALTER TABLE public.products ADD COLUMN description text") {
+		t.Errorf("Output missing ADD COLUMN for description\nFull output:\n%s", output)
+	}
+	if !strings.Contains(output, "DO $$") {
+		t.Errorf("Output missing DO block\nFull output:\n%s", output)
+	}
+}

pkg/writers/sqlexec/README.md

@@ -4,7 +4,7 @@ The SQL Executor Writer (`sqlexec`) executes SQL scripts from `models.Script` ob
 
 ## Features
 
-- **Ordered Execution**: Scripts execute in Priority→Sequence order
+- **Ordered Execution**: Scripts execute in Priority→Sequence→Name order
 - **PostgreSQL Support**: Uses `pgx/v5` driver for robust PostgreSQL connectivity
 - **Stop on Error**: Execution halts immediately on first error (default behavior)
 - **Progress Reporting**: Prints execution status to stdout
@@ -103,19 +103,40 @@ Scripts are sorted and executed based on:
 
 1. **Priority** (ascending): Lower priority values execute first
 2. **Sequence** (ascending): Within same priority, lower sequence values execute first
+3. **Name** (ascending): Within same priority and sequence, alphabetical order by name
 
 ### Example Execution Order
 
 Given these scripts:
 ```
-Script A: Priority=2, Sequence=1
+Script A: Priority=2, Sequence=1, Name="zebra"
-Script B: Priority=1, Sequence=3
+Script B: Priority=1, Sequence=3, Name="script"
-Script C: Priority=1, Sequence=1
+Script C: Priority=1, Sequence=1, Name="apple"
-Script D: Priority=1, Sequence=2
+Script D: Priority=1, Sequence=1, Name="beta"
-Script E: Priority=3, Sequence=1
+Script E: Priority=3, Sequence=1, Name="script"
 ```
 
-Execution order: **C → D → B → A → E**
+Execution order: **C (apple) → D (beta) → B → A → E**
+
+### Directory-based Sorting Example
+
+Given these files:
+```
+1_001_create_schema.sql
+1_001_create_users.sql      ← Alphabetically before "drop_tables"
+1_001_drop_tables.sql
+1_002_add_indexes.sql
+2_001_constraints.sql
+```
+
+Execution order (note alphabetical sorting at same priority/sequence):
+```
+1_001_create_schema.sql
+1_001_create_users.sql
+1_001_drop_tables.sql
+1_002_add_indexes.sql
+2_001_constraints.sql
+```
 
 ## Output
 

pkg/writers/sqlexec/writer.go

@@ -86,20 +86,23 @@ func (w *Writer) WriteTable(table *models.Table) error {
 	return fmt.Errorf("WriteTable is not supported for SQL script execution")
 }
 
-// executeScripts executes scripts in Priority then Sequence order
+// executeScripts executes scripts in Priority, Sequence, then Name order
 func (w *Writer) executeScripts(ctx context.Context, conn *pgx.Conn, scripts []*models.Script) error {
 	if len(scripts) == 0 {
 		return nil
 	}
 
-	// Sort scripts by Priority (ascending) then Sequence (ascending)
+	// Sort scripts by Priority (ascending), Sequence (ascending), then Name (ascending)
 	sortedScripts := make([]*models.Script, len(scripts))
 	copy(sortedScripts, scripts)
 	sort.Slice(sortedScripts, func(i, j int) bool {
 		if sortedScripts[i].Priority != sortedScripts[j].Priority {
 			return sortedScripts[i].Priority < sortedScripts[j].Priority
 		}
-		return sortedScripts[i].Sequence < sortedScripts[j].Sequence
+		if sortedScripts[i].Sequence != sortedScripts[j].Sequence {
+			return sortedScripts[i].Sequence < sortedScripts[j].Sequence
+		}
+		return sortedScripts[i].Name < sortedScripts[j].Name
 	})
 
 	// Execute each script in order

pkg/writers/sqlexec/writer_test.go

@@ -99,13 +99,13 @@ func TestWriter_WriteTable(t *testing.T) {
 	}
 }
 
-// TestScriptSorting verifies that scripts are sorted correctly by Priority then Sequence
+// TestScriptSorting verifies that scripts are sorted correctly by Priority, Sequence, then Name
 func TestScriptSorting(t *testing.T) {
 	scripts := []*models.Script{
-		{Name: "script1", Priority: 2, Sequence: 1, SQL: "SELECT 1;"},
+		{Name: "z_script1", Priority: 2, Sequence: 1, SQL: "SELECT 1;"},
 		{Name: "script2", Priority: 1, Sequence: 3, SQL: "SELECT 2;"},
-		{Name: "script3", Priority: 1, Sequence: 1, SQL: "SELECT 3;"},
+		{Name: "a_script3", Priority: 1, Sequence: 1, SQL: "SELECT 3;"},
-		{Name: "script4", Priority: 1, Sequence: 2, SQL: "SELECT 4;"},
+		{Name: "b_script4", Priority: 1, Sequence: 1, SQL: "SELECT 4;"},
 		{Name: "script5", Priority: 3, Sequence: 1, SQL: "SELECT 5;"},
 		{Name: "script6", Priority: 2, Sequence: 2, SQL: "SELECT 6;"},
 	}
@@ -114,25 +114,35 @@ func TestScriptSorting(t *testing.T) {
 	sortedScripts := make([]*models.Script, len(scripts))
 	copy(sortedScripts, scripts)
 
-	// Use the same sorting logic from executeScripts
+	// Sort by Priority, Sequence, then Name (matching executeScripts logic)
 	for i := 0; i < len(sortedScripts)-1; i++ {
 		for j := i + 1; j < len(sortedScripts); j++ {
-			if sortedScripts[i].Priority > sortedScripts[j].Priority ||
+			si, sj := sortedScripts[i], sortedScripts[j]
-				(sortedScripts[i].Priority == sortedScripts[j].Priority &&
+			// Compare by priority first
-					sortedScripts[i].Sequence > sortedScripts[j].Sequence) {
+			if si.Priority > sj.Priority {
 				sortedScripts[i], sortedScripts[j] = sortedScripts[j], sortedScripts[i]
+			} else if si.Priority == sj.Priority {
+				// If same priority, compare by sequence
+				if si.Sequence > sj.Sequence {
+					sortedScripts[i], sortedScripts[j] = sortedScripts[j], sortedScripts[i]
+				} else if si.Sequence == sj.Sequence {
+					// If same sequence, compare by name
+					if si.Name > sj.Name {
+						sortedScripts[i], sortedScripts[j] = sortedScripts[j], sortedScripts[i]
+					}
+				}
 			}
 		}
 	}
 
-	// Expected order after sorting
+	// Expected order after sorting (Priority -> Sequence -> Name)
 	expectedOrder := []string{
-		"script3", // Priority 1, Sequence 1
+		"a_script3", // Priority 1, Sequence 1, Name a_script3
-		"script4", // Priority 1, Sequence 2
+		"b_script4", // Priority 1, Sequence 1, Name b_script4
-		"script2", // Priority 1, Sequence 3
+		"script2",   // Priority 1, Sequence 3
-		"script1", // Priority 2, Sequence 1
+		"z_script1", // Priority 2, Sequence 1
-		"script6", // Priority 2, Sequence 2
+		"script6",   // Priority 2, Sequence 2
-		"script5", // Priority 3, Sequence 1
+		"script5",   // Priority 3, Sequence 1
 	}
 
 	for i, expected := range expectedOrder {
@@ -153,6 +163,13 @@ func TestScriptSorting(t *testing.T) {
 			t.Errorf("Sequence not ascending at position %d with same priority %d: %d > %d",
 				i, sortedScripts[i].Priority, sortedScripts[i].Sequence, sortedScripts[i+1].Sequence)
 		}
+		// Within same priority and sequence, names should be ascending
+		if sortedScripts[i].Priority == sortedScripts[i+1].Priority &&
+			sortedScripts[i].Sequence == sortedScripts[i+1].Sequence &&
+			sortedScripts[i].Name > sortedScripts[i+1].Name {
+			t.Errorf("Name not ascending at position %d with same priority/sequence: %s > %s",
+				i, sortedScripts[i].Name, sortedScripts[i+1].Name)
+		}
 	}
 }