feat(writer): 🎉 Add support for check constraints in schema generation

* Implement check constraints in the schema writer.
* Generate SQL statements to add check constraints if they do not exist.
* Add tests to verify correct generation of check constraints.

cmd/relspec/scripts.go

@@ -14,10 +14,11 @@ import (
 )
 
 var (
-	scriptsDir        string
+	scriptsDir          string
-	scriptsConn       string
+	scriptsConn         string
-	scriptsSchemaName string
+	scriptsSchemaName   string
-	scriptsDBName     string
+	scriptsDBName       string
+	scriptsIgnoreErrors bool
 )
 
 var scriptsCmd = &cobra.Command{
@@ -62,7 +63,7 @@ var scriptsExecuteCmd = &cobra.Command{
 	Long: `Execute SQL scripts from a directory against a PostgreSQL database.
 
 Scripts are executed in order: Priority (ascending), Sequence (ascending), Name (alphabetical).
-Execution stops immediately on the first error.
+By default, execution stops immediately on the first error. Use --ignore-errors to continue execution.
 
 The directory is scanned recursively for all subdirectories and files matching the patterns:
   {priority}_{sequence}_{name}.sql or .pgsql (underscore format)
@@ -86,7 +87,12 @@ Examples:
 
   # Execute with SSL disabled
   relspec scripts execute --dir ./sql \
-                          --conn "postgres://user:pass@localhost/db?sslmode=disable"`,
+                          --conn "postgres://user:pass@localhost/db?sslmode=disable"
+
+  # Continue executing even if errors occur
+  relspec scripts execute --dir ./migrations \
+                          --conn "postgres://localhost/mydb" \
+                          --ignore-errors`,
 	RunE: runScriptsExecute,
 }
 
@@ -105,6 +111,7 @@ func init() {
 	scriptsExecuteCmd.Flags().StringVar(&scriptsConn, "conn", "", "PostgreSQL connection string (required)")
 	scriptsExecuteCmd.Flags().StringVar(&scriptsSchemaName, "schema", "public", "Schema name (optional, default: public)")
 	scriptsExecuteCmd.Flags().StringVar(&scriptsDBName, "database", "database", "Database name (optional, default: database)")
+	scriptsExecuteCmd.Flags().BoolVar(&scriptsIgnoreErrors, "ignore-errors", false, "Continue executing scripts even if errors occur")
 
 	err = scriptsExecuteCmd.MarkFlagRequired("dir")
 	if err != nil {
@@ -250,17 +257,39 @@ func runScriptsExecute(cmd *cobra.Command, args []string) error {
 	writer := sqlexec.NewWriter(&writers.WriterOptions{
 		Metadata: map[string]any{
 			"connection_string": scriptsConn,
+			"ignore_errors":     scriptsIgnoreErrors,
 		},
 	})
 
 	if err := writer.WriteSchema(schema); err != nil {
 		fmt.Fprintf(os.Stderr, "\n")
-		return fmt.Errorf("execution failed: %w", err)
+		return fmt.Errorf("script execution failed: %w", err)
+	}
+
+	// Get execution results from writer metadata
+	totalCount := len(schema.Scripts)
+	successCount := totalCount
+	failedCount := 0
+
+	opts := writer.Options()
+	if total, exists := opts.Metadata["execution_total"].(int); exists {
+		totalCount = total
+	}
+	if success, exists := opts.Metadata["execution_success"].(int); exists {
+		successCount = success
+	}
+	if failed, exists := opts.Metadata["execution_failed"].(int); exists {
+		failedCount = failed
 	}
 
 	fmt.Fprintf(os.Stderr, "\n=== Execution Complete ===\n")
 	fmt.Fprintf(os.Stderr, "Completed at: %s\n", getCurrentTimestamp())
-	fmt.Fprintf(os.Stderr, "Successfully executed %d script(s)\n\n", len(schema.Scripts))
+	fmt.Fprintf(os.Stderr, "Total scripts: %d\n", totalCount)
+	fmt.Fprintf(os.Stderr, "Successful:    %d\n", successCount)
+	if failedCount > 0 {
+		fmt.Fprintf(os.Stderr, "Failed:        %d\n", failedCount)
+	}
+	fmt.Fprintf(os.Stderr, "\n")
 
 	return nil
 }

pkg/readers/dbml/reader.go

@@ -128,6 +128,46 @@ func (r *Reader) readDirectoryDBML(dirPath string) (*models.Database, error) {
 	return db, nil
 }
 
+// splitIdentifier splits a dotted identifier while respecting quotes
+// Handles cases like: "schema.with.dots"."table"."column"
+func splitIdentifier(s string) []string {
+	var parts []string
+	var current strings.Builder
+	inQuote := false
+	quoteChar := byte(0)
+
+	for i := 0; i < len(s); i++ {
+		ch := s[i]
+
+		if !inQuote {
+			switch ch {
+			case '"', '\'':
+				inQuote = true
+				quoteChar = ch
+				current.WriteByte(ch)
+			case '.':
+				if current.Len() > 0 {
+					parts = append(parts, current.String())
+					current.Reset()
+				}
+			default:
+				current.WriteByte(ch)
+			}
+		} else {
+			current.WriteByte(ch)
+			if ch == quoteChar {
+				inQuote = false
+			}
+		}
+	}
+
+	if current.Len() > 0 {
+		parts = append(parts, current.String())
+	}
+
+	return parts
+}
+
 // stripQuotes removes surrounding quotes and comments from an identifier
 func stripQuotes(s string) string {
 	s = strings.TrimSpace(s)
@@ -409,7 +449,9 @@ func (r *Reader) parseDBML(content string) (*models.Database, error) {
 		// Parse Table definition
 		if matches := tableRegex.FindStringSubmatch(line); matches != nil {
 			tableName := matches[1]
-			parts := strings.Split(tableName, ".")
+			// Strip comments/notes before parsing to avoid dots in notes
+			tableName = strings.TrimSpace(regexp.MustCompile(`\s*\[.*?\]\s*`).ReplaceAllString(tableName, ""))
+			parts := splitIdentifier(tableName)
 
 			if len(parts) == 2 {
 				currentSchema = stripQuotes(parts[0])
@@ -562,7 +604,7 @@ func (r *Reader) parseColumn(line, tableName, schemaName string) (*models.Column
 				} else if attr == "unique" {
 					// Create a unique constraint
 					uniqueConstraint := models.InitConstraint(
-						fmt.Sprintf("uq_%s", columnName),
+						fmt.Sprintf("uq_%s_%s", tableName, columnName),
 						models.UniqueConstraint,
 					)
 					uniqueConstraint.Schema = schemaName
@@ -610,8 +652,8 @@ func (r *Reader) parseColumn(line, tableName, schemaName string) (*models.Column
 							constraint.Table = tableName
 							constraint.Columns = []string{columnName}
 						}
-						// Generate short constraint name based on the column
+						// Generate constraint name based on table and columns
-						constraint.Name = fmt.Sprintf("fk_%s", constraint.Columns[0])
+						constraint.Name = fmt.Sprintf("fk_%s_%s", constraint.Table, strings.Join(constraint.Columns, "_"))
 					}
 				}
 			}
@@ -695,7 +737,11 @@ func (r *Reader) parseIndex(line, tableName, schemaName string) *models.Index {
 
 	// Generate name if not provided
 	if index.Name == "" {
-		index.Name = fmt.Sprintf("idx_%s_%s", tableName, strings.Join(columns, "_"))
+		prefix := "idx"
+		if index.Unique {
+			prefix = "uidx"
+		}
+		index.Name = fmt.Sprintf("%s_%s_%s", prefix, tableName, strings.Join(columns, "_"))
 	}
 
 	return index
@@ -755,10 +801,10 @@ func (r *Reader) parseRef(refStr string) *models.Constraint {
 		return nil
 	}
 
-	// Generate short constraint name based on the source column
+	// Generate constraint name based on table and columns
-	constraintName := fmt.Sprintf("fk_%s_%s", fromTable, toTable)
+	constraintName := fmt.Sprintf("fk_%s_%s", fromTable, strings.Join(fromColumns, "_"))
-	if len(fromColumns) > 0 {
+	if len(fromColumns) == 0 {
-		constraintName = fmt.Sprintf("fk_%s", fromColumns[0])
+		constraintName = fmt.Sprintf("fk_%s_%s", fromTable, toTable)
 	}
 
 	constraint := models.InitConstraint(
@@ -814,7 +860,7 @@ func (r *Reader) parseTableRef(ref string) (schema, table string, columns []stri
 	}
 
 	// Parse schema, table, and optionally column
-	parts := strings.Split(strings.TrimSpace(ref), ".")
+	parts := splitIdentifier(strings.TrimSpace(ref))
 	if len(parts) == 3 {
 		// Format: "schema"."table"."column"
 		schema = stripQuotes(parts[0])

pkg/readers/dbml/reader_test.go

@@ -777,6 +777,76 @@ func TestParseFilePrefix(t *testing.T) {
 	}
 }
 
+func TestConstraintNaming(t *testing.T) {
+	// Test that constraints are named with proper prefixes
+	opts := &readers.ReaderOptions{
+		FilePath: filepath.Join("..", "..", "..", "tests", "assets", "dbml", "complex.dbml"),
+	}
+
+	reader := NewReader(opts)
+	db, err := reader.ReadDatabase()
+	if err != nil {
+		t.Fatalf("ReadDatabase() error = %v", err)
+	}
+
+	// Find users table
+	var usersTable *models.Table
+	var postsTable *models.Table
+	for _, schema := range db.Schemas {
+		for _, table := range schema.Tables {
+			if table.Name == "users" {
+				usersTable = table
+			} else if table.Name == "posts" {
+				postsTable = table
+			}
+		}
+	}
+
+	if usersTable == nil {
+		t.Fatal("Users table not found")
+	}
+	if postsTable == nil {
+		t.Fatal("Posts table not found")
+	}
+
+	// Test unique constraint naming: uq_table_column
+	if _, exists := usersTable.Constraints["uq_users_email"]; !exists {
+		t.Error("Expected unique constraint 'uq_users_email' not found")
+		t.Logf("Available constraints: %v", getKeys(usersTable.Constraints))
+	}
+
+	if _, exists := postsTable.Constraints["uq_posts_slug"]; !exists {
+		t.Error("Expected unique constraint 'uq_posts_slug' not found")
+		t.Logf("Available constraints: %v", getKeys(postsTable.Constraints))
+	}
+
+	// Test foreign key naming: fk_table_column
+	if _, exists := postsTable.Constraints["fk_posts_user_id"]; !exists {
+		t.Error("Expected foreign key 'fk_posts_user_id' not found")
+		t.Logf("Available constraints: %v", getKeys(postsTable.Constraints))
+	}
+
+	// Test unique index naming: uidx_table_columns
+	if _, exists := postsTable.Indexes["uidx_posts_slug"]; !exists {
+		t.Error("Expected unique index 'uidx_posts_slug' not found")
+		t.Logf("Available indexes: %v", getKeys(postsTable.Indexes))
+	}
+
+	// Test regular index naming: idx_table_columns
+	if _, exists := postsTable.Indexes["idx_posts_user_id_published"]; !exists {
+		t.Error("Expected index 'idx_posts_user_id_published' not found")
+		t.Logf("Available indexes: %v", getKeys(postsTable.Indexes))
+	}
+}
+
+func getKeys[V any](m map[string]V) []string {
+	keys := make([]string, 0, len(m))
+	for k := range m {
+		keys = append(keys, k)
+	}
+	return keys
+}
+
 func TestHasCommentedRefs(t *testing.T) {
 	// Test with the actual multifile test fixtures
 	tests := []struct {

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
@@ -248,6 +295,56 @@ func (w *Writer) GenerateSchemaStatements(schema *models.Schema) ([]string, erro
 		}
 	}
 
+	// Phase 5.5: Unique constraints
+	for _, table := range schema.Tables {
+		for _, constraint := range table.Constraints {
+			if constraint.Type != models.UniqueConstraint {
+				continue
+			}
+
+			// Wrap in DO block to check for existing constraint
+			stmt := fmt.Sprintf("DO $$\nBEGIN\n"+
+				"  IF NOT EXISTS (\n"+
+				"    SELECT 1 FROM information_schema.table_constraints\n"+
+				"    WHERE table_schema = '%s'\n"+
+				"      AND table_name = '%s'\n"+
+				"      AND constraint_name = '%s'\n"+
+				"  ) THEN\n"+
+				"    ALTER TABLE %s.%s ADD CONSTRAINT %s UNIQUE (%s);\n"+
+				"  END IF;\n"+
+				"END;\n$$",
+				schema.Name, table.Name, constraint.Name,
+				schema.SQLName(), table.SQLName(), constraint.Name,
+				strings.Join(constraint.Columns, ", "))
+			statements = append(statements, stmt)
+		}
+	}
+
+	// Phase 5.7: Check constraints
+	for _, table := range schema.Tables {
+		for _, constraint := range table.Constraints {
+			if constraint.Type != models.CheckConstraint {
+				continue
+			}
+
+			// Wrap in DO block to check for existing constraint
+			stmt := fmt.Sprintf("DO $$\nBEGIN\n"+
+				"  IF NOT EXISTS (\n"+
+				"    SELECT 1 FROM information_schema.table_constraints\n"+
+				"    WHERE table_schema = '%s'\n"+
+				"      AND table_name = '%s'\n"+
+				"      AND constraint_name = '%s'\n"+
+				"  ) THEN\n"+
+				"    ALTER TABLE %s.%s ADD CONSTRAINT %s CHECK (%s);\n"+
+				"  END IF;\n"+
+				"END;\n$$",
+				schema.Name, table.Name, constraint.Name,
+				schema.SQLName(), table.SQLName(), constraint.Name,
+				constraint.Expression)
+			statements = append(statements, stmt)
+		}
+	}
+
 	// Phase 6: Foreign keys
 	for _, table := range schema.Tables {
 		for _, constraint := range table.Constraints {
@@ -270,7 +367,18 @@ 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 +408,68 @@ 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 +492,7 @@ 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 +506,25 @@ 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 +577,11 @@ 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
@@ -406,6 +592,16 @@ func (w *Writer) WriteSchema(schema *models.Schema) error {
 		return err
 	}
 
+	// Phase 5.5: Create unique constraints (priority 185)
+	if err := w.writeUniqueConstraints(schema); err != nil {
+		return err
+	}
+
+	// Phase 5.7: Create check constraints (priority 190)
+	if err := w.writeCheckConstraints(schema); err != nil {
+		return err
+	}
+
 	// Phase 6: Create foreign key constraints (priority 195)
 	if err := w.writeForeignKeys(schema); err != nil {
 		return err
@@ -437,6 +633,44 @@ 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 +724,8 @@ 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 +736,35 @@ 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 +806,32 @@ 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)
@@ -644,6 +925,97 @@ func (w *Writer) writeIndexes(schema *models.Schema) error {
 	return nil
 }
 
+// writeUniqueConstraints generates ALTER TABLE statements for unique constraints
+func (w *Writer) writeUniqueConstraints(schema *models.Schema) error {
+	fmt.Fprintf(w.writer, "-- Unique constraints for schema: %s\n", schema.Name)
+
+	for _, table := range schema.Tables {
+		// Sort constraints by name for consistent output
+		constraintNames := make([]string, 0, len(table.Constraints))
+		for name, constraint := range table.Constraints {
+			if constraint.Type == models.UniqueConstraint {
+				constraintNames = append(constraintNames, name)
+			}
+		}
+		sort.Strings(constraintNames)
+
+		for _, name := range constraintNames {
+			constraint := table.Constraints[name]
+
+			// Build column list
+			columnExprs := make([]string, 0, len(constraint.Columns))
+			for _, colName := range constraint.Columns {
+				if col, ok := table.Columns[colName]; ok {
+					columnExprs = append(columnExprs, col.SQLName())
+				}
+			}
+
+			if len(columnExprs) == 0 {
+				continue
+			}
+
+			// Wrap in DO block to check for existing constraint
+			fmt.Fprintf(w.writer, "DO $$\n")
+			fmt.Fprintf(w.writer, "BEGIN\n")
+			fmt.Fprintf(w.writer, "  IF NOT EXISTS (\n")
+			fmt.Fprintf(w.writer, "    SELECT 1 FROM information_schema.table_constraints\n")
+			fmt.Fprintf(w.writer, "    WHERE table_schema = '%s'\n", schema.Name)
+			fmt.Fprintf(w.writer, "      AND table_name = '%s'\n", table.Name)
+			fmt.Fprintf(w.writer, "      AND constraint_name = '%s'\n", constraint.Name)
+			fmt.Fprintf(w.writer, "  ) THEN\n")
+			fmt.Fprintf(w.writer, "    ALTER TABLE %s.%s ADD CONSTRAINT %s UNIQUE (%s);\n",
+				schema.SQLName(), table.SQLName(), constraint.Name, strings.Join(columnExprs, ", "))
+			fmt.Fprintf(w.writer, "  END IF;\n")
+			fmt.Fprintf(w.writer, "END;\n")
+			fmt.Fprintf(w.writer, "$$;\n\n")
+		}
+	}
+
+	return nil
+}
+
+// writeCheckConstraints generates ALTER TABLE statements for check constraints
+func (w *Writer) writeCheckConstraints(schema *models.Schema) error {
+	fmt.Fprintf(w.writer, "-- Check constraints for schema: %s\n", schema.Name)
+
+	for _, table := range schema.Tables {
+		// Sort constraints by name for consistent output
+		constraintNames := make([]string, 0, len(table.Constraints))
+		for name, constraint := range table.Constraints {
+			if constraint.Type == models.CheckConstraint {
+				constraintNames = append(constraintNames, name)
+			}
+		}
+		sort.Strings(constraintNames)
+
+		for _, name := range constraintNames {
+			constraint := table.Constraints[name]
+
+			// Skip if expression is empty
+			if constraint.Expression == "" {
+				continue
+			}
+
+			// Wrap in DO block to check for existing constraint
+			fmt.Fprintf(w.writer, "DO $$\n")
+			fmt.Fprintf(w.writer, "BEGIN\n")
+			fmt.Fprintf(w.writer, "  IF NOT EXISTS (\n")
+			fmt.Fprintf(w.writer, "    SELECT 1 FROM information_schema.table_constraints\n")
+			fmt.Fprintf(w.writer, "    WHERE table_schema = '%s'\n", schema.Name)
+			fmt.Fprintf(w.writer, "      AND table_name = '%s'\n", table.Name)
+			fmt.Fprintf(w.writer, "      AND constraint_name = '%s'\n", constraint.Name)
+			fmt.Fprintf(w.writer, "  ) THEN\n")
+			fmt.Fprintf(w.writer, "    ALTER TABLE %s.%s ADD CONSTRAINT %s CHECK (%s);\n",
+				schema.SQLName(), table.SQLName(), constraint.Name, constraint.Expression)
+			fmt.Fprintf(w.writer, "  END IF;\n")
+			fmt.Fprintf(w.writer, "END;\n")
+			fmt.Fprintf(w.writer, "$$;\n\n")
+		}
+	}
+
+	return nil
+}
+
 // writeForeignKeys generates ALTER TABLE statements for foreign keys
 func (w *Writer) writeForeignKeys(schema *models.Schema) error {
 	fmt.Fprintf(w.writer, "-- Foreign keys for schema: %s\n", schema.Name)
@@ -711,13 +1083,6 @@ 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 == "" {
@@ -728,11 +1093,102 @@ 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")
+		}
+
+		// Also process any foreign key constraints that don't have a relationship
+		processedConstraints := make(map[string]bool)
+		for _, rel := range table.Relationships {
+			fkName := rel.ForeignKey
+			if fkName == "" {
+				fkName = rel.Name
+			}
+			if fkName != "" {
+				processedConstraints[fkName] = true
+			}
+		}
+
+		// Find unprocessed foreign key constraints
+		constraintNames := make([]string, 0)
+		for name, constraint := range table.Constraints {
+			if constraint.Type == models.ForeignKeyConstraint && !processedConstraints[name] {
+				constraintNames = append(constraintNames, name)
+			}
+		}
+		sort.Strings(constraintNames)
+
+		for _, name := range constraintNames {
+			constraint := table.Constraints[name]
+
+			// Build column lists
+			sourceColumns := make([]string, 0, len(constraint.Columns))
+			for _, colName := range constraint.Columns {
+				if col, ok := table.Columns[colName]; ok {
+					sourceColumns = append(sourceColumns, col.SQLName())
+				} else {
+					sourceColumns = append(sourceColumns, colName)
+				}
+			}
+
+			targetColumns := make([]string, 0, len(constraint.ReferencedColumns))
+			for _, colName := range constraint.ReferencedColumns {
+				targetColumns = append(targetColumns, strings.ToLower(colName))
+			}
+
+			if len(sourceColumns) == 0 || len(targetColumns) == 0 {
+				continue
+			}
+
+			onDelete := "NO ACTION"
+			if constraint.OnDelete != "" {
+				onDelete = strings.ToUpper(constraint.OnDelete)
+			}
+
+			onUpdate := "NO ACTION"
+			if constraint.OnUpdate != "" {
+				onUpdate = strings.ToUpper(constraint.OnUpdate)
+			}
+
+			refSchema := constraint.ReferencedSchema
+			if refSchema == "" {
+				refSchema = schema.Name
+			}
+			refTable := constraint.ReferencedTable
+
+			// Use DO block to check if constraint exists before adding
+			fmt.Fprintf(w.writer, "DO $$\nBEGIN\n")
+			fmt.Fprintf(w.writer, "  IF NOT EXISTS (\n")
+			fmt.Fprintf(w.writer, "    SELECT 1 FROM information_schema.table_constraints\n")
+			fmt.Fprintf(w.writer, "    WHERE table_schema = '%s'\n", schema.Name)
+			fmt.Fprintf(w.writer, "      AND table_name = '%s'\n", table.Name)
+			fmt.Fprintf(w.writer, "      AND constraint_name = '%s'\n", constraint.Name)
+			fmt.Fprintf(w.writer, "  ) THEN\n")
+			fmt.Fprintf(w.writer, "    ALTER TABLE %s.%s\n", schema.SQLName(), table.SQLName())
+			fmt.Fprintf(w.writer, "      ADD CONSTRAINT %s\n", constraint.Name)
+			fmt.Fprintf(w.writer, "      FOREIGN KEY (%s)\n", strings.Join(sourceColumns, ", "))
+			fmt.Fprintf(w.writer, "      REFERENCES %s.%s (%s)\n",
+				refSchema, refTable, strings.Join(targetColumns, ", "))
+			fmt.Fprintf(w.writer, "      ON DELETE %s\n", onDelete)
+			fmt.Fprintf(w.writer, "      ON UPDATE %s;\n", onUpdate)
+			fmt.Fprintf(w.writer, "  END IF;\n")
+			fmt.Fprintf(w.writer, "END;\n$$;\n\n")
 		}
 	}
 
@@ -844,6 +1300,44 @@ 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

@@ -164,6 +164,296 @@ func TestWriteForeignKeys(t *testing.T) {
 	}
 }
 
+func TestWriteUniqueConstraints(t *testing.T) {
+	// Create a test database with unique constraints
+	db := models.InitDatabase("testdb")
+	schema := models.InitSchema("public")
+
+	// Create table with unique constraints
+	table := models.InitTable("users", "public")
+
+	// Add columns
+	emailCol := models.InitColumn("email", "users", "public")
+	emailCol.Type = "varchar(255)"
+	emailCol.NotNull = true
+	table.Columns["email"] = emailCol
+
+	guidCol := models.InitColumn("guid", "users", "public")
+	guidCol.Type = "uuid"
+	guidCol.NotNull = true
+	table.Columns["guid"] = guidCol
+
+	// Add unique constraints
+	emailConstraint := &models.Constraint{
+		Name:    "uq_email",
+		Type:    models.UniqueConstraint,
+		Schema:  "public",
+		Table:   "users",
+		Columns: []string{"email"},
+	}
+	table.Constraints["uq_email"] = emailConstraint
+
+	guidConstraint := &models.Constraint{
+		Name:    "uq_guid",
+		Type:    models.UniqueConstraint,
+		Schema:  "public",
+		Table:   "users",
+		Columns: []string{"guid"},
+	}
+	table.Constraints["uq_guid"] = guidConstraint
+
+	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 the database
+	err := writer.WriteDatabase(db)
+	if err != nil {
+		t.Fatalf("WriteDatabase failed: %v", err)
+	}
+
+	output := buf.String()
+
+	// Print output for debugging
+	t.Logf("Generated SQL:\n%s", output)
+
+	// Verify unique constraints are present
+	if !strings.Contains(output, "-- Unique constraints for schema: public") {
+		t.Errorf("Output missing unique constraints header")
+	}
+	if !strings.Contains(output, "ADD CONSTRAINT uq_email UNIQUE (email)") {
+		t.Errorf("Output missing uq_email unique constraint\nFull output:\n%s", output)
+	}
+	if !strings.Contains(output, "ADD CONSTRAINT uq_guid UNIQUE (guid)") {
+		t.Errorf("Output missing uq_guid unique constraint\nFull output:\n%s", output)
+	}
+}
+
+func TestWriteCheckConstraints(t *testing.T) {
+	// Create a test database with check constraints
+	db := models.InitDatabase("testdb")
+	schema := models.InitSchema("public")
+
+	// Create table with check constraints
+	table := models.InitTable("products", "public")
+
+	// Add columns
+	priceCol := models.InitColumn("price", "products", "public")
+	priceCol.Type = "numeric(10,2)"
+	table.Columns["price"] = priceCol
+
+	statusCol := models.InitColumn("status", "products", "public")
+	statusCol.Type = "varchar(20)"
+	table.Columns["status"] = statusCol
+
+	quantityCol := models.InitColumn("quantity", "products", "public")
+	quantityCol.Type = "integer"
+	table.Columns["quantity"] = quantityCol
+
+	// Add check constraints
+	priceConstraint := &models.Constraint{
+		Name:       "ck_price_positive",
+		Type:       models.CheckConstraint,
+		Schema:     "public",
+		Table:      "products",
+		Expression: "price >= 0",
+	}
+	table.Constraints["ck_price_positive"] = priceConstraint
+
+	statusConstraint := &models.Constraint{
+		Name:       "ck_status_valid",
+		Type:       models.CheckConstraint,
+		Schema:     "public",
+		Table:      "products",
+		Expression: "status IN ('active', 'inactive', 'discontinued')",
+	}
+	table.Constraints["ck_status_valid"] = statusConstraint
+
+	quantityConstraint := &models.Constraint{
+		Name:       "ck_quantity_nonnegative",
+		Type:       models.CheckConstraint,
+		Schema:     "public",
+		Table:      "products",
+		Expression: "quantity >= 0",
+	}
+	table.Constraints["ck_quantity_nonnegative"] = quantityConstraint
+
+	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 the database
+	err := writer.WriteDatabase(db)
+	if err != nil {
+		t.Fatalf("WriteDatabase failed: %v", err)
+	}
+
+	output := buf.String()
+
+	// Print output for debugging
+	t.Logf("Generated SQL:\n%s", output)
+
+	// Verify check constraints are present
+	if !strings.Contains(output, "-- Check constraints for schema: public") {
+		t.Errorf("Output missing check constraints header")
+	}
+	if !strings.Contains(output, "ADD CONSTRAINT ck_price_positive CHECK (price >= 0)") {
+		t.Errorf("Output missing ck_price_positive check constraint\nFull output:\n%s", output)
+	}
+	if !strings.Contains(output, "ADD CONSTRAINT ck_status_valid CHECK (status IN ('active', 'inactive', 'discontinued'))") {
+		t.Errorf("Output missing ck_status_valid check constraint\nFull output:\n%s", output)
+	}
+	if !strings.Contains(output, "ADD CONSTRAINT ck_quantity_nonnegative CHECK (quantity >= 0)") {
+		t.Errorf("Output missing ck_quantity_nonnegative check constraint\nFull output:\n%s", output)
+	}
+}
+
+func TestWriteAllConstraintTypes(t *testing.T) {
+	// Create a comprehensive test with all constraint types
+	db := models.InitDatabase("testdb")
+	schema := models.InitSchema("public")
+
+	// Create orders table
+	ordersTable := models.InitTable("orders", "public")
+
+	// Add columns
+	idCol := models.InitColumn("id", "orders", "public")
+	idCol.Type = "integer"
+	idCol.IsPrimaryKey = true
+	ordersTable.Columns["id"] = idCol
+
+	userIDCol := models.InitColumn("user_id", "orders", "public")
+	userIDCol.Type = "integer"
+	userIDCol.NotNull = true
+	ordersTable.Columns["user_id"] = userIDCol
+
+	orderNumberCol := models.InitColumn("order_number", "orders", "public")
+	orderNumberCol.Type = "varchar(50)"
+	orderNumberCol.NotNull = true
+	ordersTable.Columns["order_number"] = orderNumberCol
+
+	totalCol := models.InitColumn("total", "orders", "public")
+	totalCol.Type = "numeric(10,2)"
+	ordersTable.Columns["total"] = totalCol
+
+	statusCol := models.InitColumn("status", "orders", "public")
+	statusCol.Type = "varchar(20)"
+	ordersTable.Columns["status"] = statusCol
+
+	// Add primary key constraint
+	pkConstraint := &models.Constraint{
+		Name:    "pk_orders",
+		Type:    models.PrimaryKeyConstraint,
+		Schema:  "public",
+		Table:   "orders",
+		Columns: []string{"id"},
+	}
+	ordersTable.Constraints["pk_orders"] = pkConstraint
+
+	// Add unique constraint
+	uniqueConstraint := &models.Constraint{
+		Name:    "uq_order_number",
+		Type:    models.UniqueConstraint,
+		Schema:  "public",
+		Table:   "orders",
+		Columns: []string{"order_number"},
+	}
+	ordersTable.Constraints["uq_order_number"] = uniqueConstraint
+
+	// Add check constraint
+	checkConstraint := &models.Constraint{
+		Name:       "ck_total_positive",
+		Type:       models.CheckConstraint,
+		Schema:     "public",
+		Table:      "orders",
+		Expression: "total > 0",
+	}
+	ordersTable.Constraints["ck_total_positive"] = checkConstraint
+
+	statusCheckConstraint := &models.Constraint{
+		Name:       "ck_status_valid",
+		Type:       models.CheckConstraint,
+		Schema:     "public",
+		Table:      "orders",
+		Expression: "status IN ('pending', 'completed', 'cancelled')",
+	}
+	ordersTable.Constraints["ck_status_valid"] = statusCheckConstraint
+
+	// Add foreign key constraint (referencing a users table)
+	fkConstraint := &models.Constraint{
+		Name:              "fk_orders_user",
+		Type:              models.ForeignKeyConstraint,
+		Schema:            "public",
+		Table:             "orders",
+		Columns:           []string{"user_id"},
+		ReferencedSchema:  "public",
+		ReferencedTable:   "users",
+		ReferencedColumns: []string{"id"},
+		OnDelete:          "CASCADE",
+		OnUpdate:          "CASCADE",
+	}
+	ordersTable.Constraints["fk_orders_user"] = fkConstraint
+
+	schema.Tables = append(schema.Tables, ordersTable)
+	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 the database
+	err := writer.WriteDatabase(db)
+	if err != nil {
+		t.Fatalf("WriteDatabase failed: %v", err)
+	}
+
+	output := buf.String()
+
+	// Print output for debugging
+	t.Logf("Generated SQL:\n%s", output)
+
+	// Verify all constraint types are present
+	expectedConstraints := map[string]string{
+		"Primary Key":      "PRIMARY KEY",
+		"Unique":           "ADD CONSTRAINT uq_order_number UNIQUE (order_number)",
+		"Check (total)":    "ADD CONSTRAINT ck_total_positive CHECK (total > 0)",
+		"Check (status)":   "ADD CONSTRAINT ck_status_valid CHECK (status IN ('pending', 'completed', 'cancelled'))",
+		"Foreign Key":      "FOREIGN KEY",
+	}
+
+	for name, expected := range expectedConstraints {
+		if !strings.Contains(output, expected) {
+			t.Errorf("Output missing %s constraint: %s\nFull output:\n%s", name, expected, output)
+		}
+	}
+
+	// Verify section headers
+	sections := []string{
+		"-- Primary keys for schema: public",
+		"-- Unique constraints for schema: public",
+		"-- Check constraints for schema: public",
+		"-- Foreign keys for schema: public",
+	}
+
+	for _, section := range sections {
+		if !strings.Contains(output, section) {
+			t.Errorf("Output missing section header: %s", section)
+		}
+	}
+}
+
 func TestWriteTable(t *testing.T) {
 	// Create a single table
 	table := models.InitTable("products", "public")
@@ -305,3 +595,263 @@ 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/writer.go

@@ -23,6 +23,11 @@ func NewWriter(options *writers.WriterOptions) *Writer {
 	}
 }
 
+// Options returns the writer options (useful for reading execution results)
+func (w *Writer) Options() *writers.WriterOptions {
+	return w.options
+}
+
 // WriteDatabase executes all scripts from all schemas in the database
 func (w *Writer) WriteDatabase(db *models.Database) error {
 	if db == nil {
@@ -92,6 +97,22 @@ func (w *Writer) executeScripts(ctx context.Context, conn *pgx.Conn, scripts []*
 		return nil
 	}
 
+	// Check if we should ignore errors
+	ignoreErrors := false
+	if val, ok := w.options.Metadata["ignore_errors"].(bool); ok {
+		ignoreErrors = val
+	}
+
+	// Track failed scripts and execution counts
+	var failedScripts []struct {
+		name     string
+		priority int
+		sequence uint
+		err      error
+	}
+	successCount := 0
+	totalCount := 0
+
 	// Sort scripts by Priority (ascending), Sequence (ascending), then Name (ascending)
 	sortedScripts := make([]*models.Script, len(scripts))
 	copy(sortedScripts, scripts)
@@ -111,18 +132,49 @@ func (w *Writer) executeScripts(ctx context.Context, conn *pgx.Conn, scripts []*
 			continue
 		}
 
+		totalCount++
 		fmt.Printf("Executing script: %s (Priority=%d, Sequence=%d)\n",
 			script.Name, script.Priority, script.Sequence)
 
 		// Execute the SQL script
 		_, err := conn.Exec(ctx, script.SQL)
 		if err != nil {
-			return fmt.Errorf("failed to execute script %s (Priority=%d, Sequence=%d): %w",
+			if ignoreErrors {
+				fmt.Printf("⚠ Error executing %s: %v (continuing due to --ignore-errors)\n", script.Name, err)
+				failedScripts = append(failedScripts, struct {
+					name     string
+					priority int
+					sequence uint
+					err      error
+				}{
+					name:     script.Name,
+					priority: script.Priority,
+					sequence: script.Sequence,
+					err:      err,
+				})
+				continue
+			}
+			return fmt.Errorf("script %s (Priority=%d, Sequence=%d): %w",
 				script.Name, script.Priority, script.Sequence, err)
 		}
 
+		successCount++
 		fmt.Printf("✓ Successfully executed: %s\n", script.Name)
 	}
 
+	// Store execution results in metadata for caller
+	w.options.Metadata["execution_total"] = totalCount
+	w.options.Metadata["execution_success"] = successCount
+	w.options.Metadata["execution_failed"] = len(failedScripts)
+
+	// Print summary of failed scripts if any
+	if len(failedScripts) > 0 {
+		fmt.Printf("\n⚠ Failed Scripts Summary (%d failed):\n", len(failedScripts))
+		for i, failed := range failedScripts {
+			fmt.Printf("  %d. %s (Priority=%d, Sequence=%d)\n     Error: %v\n",
+				i+1, failed.name, failed.priority, failed.sequence, failed.err)
+		}
+	}
+
 	return nil
 }