feat(merge): 🎉 Add support for merging constraints and indexes

* Implement mergeConstraints to handle table constraints
* Implement mergeIndexes to handle table indexes
* Update mergeTables to include constraints and indexes during merge

pkg/merge/merge.go

@@ -120,8 +120,10 @@ func (r *MergeResult) mergeTables(schema *models.Schema, source *models.Schema,
 		}
 
 		if tgtTable, exists := existingTables[tableName]; exists {
-			// Table exists, merge its columns
+			// Table exists, merge its columns, constraints, and indexes
 			r.mergeColumns(tgtTable, srcTable)
+			r.mergeConstraints(tgtTable, srcTable)
+			r.mergeIndexes(tgtTable, srcTable)
 		} else {
 			// Table doesn't exist, add it
 			newTable := cloneTable(srcTable)
@@ -151,6 +153,50 @@ func (r *MergeResult) mergeColumns(table *models.Table, srcTable *models.Table)
 	}
 }
 
+func (r *MergeResult) mergeConstraints(table *models.Table, srcTable *models.Table) {
+	// Initialize constraints map if nil
+	if table.Constraints == nil {
+		table.Constraints = make(map[string]*models.Constraint)
+	}
+
+	// Create map of existing constraints
+	existingConstraints := make(map[string]*models.Constraint)
+	for constName := range table.Constraints {
+		existingConstraints[constName] = table.Constraints[constName]
+	}
+
+	// Merge constraints
+	for constName, srcConst := range srcTable.Constraints {
+		if _, exists := existingConstraints[constName]; !exists {
+			// Constraint doesn't exist, add it
+			newConst := cloneConstraint(srcConst)
+			table.Constraints[constName] = newConst
+		}
+	}
+}
+
+func (r *MergeResult) mergeIndexes(table *models.Table, srcTable *models.Table) {
+	// Initialize indexes map if nil
+	if table.Indexes == nil {
+		table.Indexes = make(map[string]*models.Index)
+	}
+
+	// Create map of existing indexes
+	existingIndexes := make(map[string]*models.Index)
+	for idxName := range table.Indexes {
+		existingIndexes[idxName] = table.Indexes[idxName]
+	}
+
+	// Merge indexes
+	for idxName, srcIdx := range srcTable.Indexes {
+		if _, exists := existingIndexes[idxName]; !exists {
+			// Index doesn't exist, add it
+			newIdx := cloneIndex(srcIdx)
+			table.Indexes[idxName] = newIdx
+		}
+	}
+}
+
 func (r *MergeResult) mergeViews(schema *models.Schema, source *models.Schema) {
 	// Create map of existing views
 	existingViews := make(map[string]*models.View)

pkg/readers/dbml/reader.go

@@ -603,8 +603,10 @@ func (r *Reader) parseColumn(line, tableName, schemaName string) (*models.Column
 					column.Default = strings.Trim(defaultVal, "'\"")
 				} else if attr == "unique" {
 					// Create a unique constraint
+					// Clean table name by removing leading underscores to avoid double underscores
+					cleanTableName := strings.TrimLeft(tableName, "_")
 					uniqueConstraint := models.InitConstraint(
-						fmt.Sprintf("uq_%s", columnName),
+						fmt.Sprintf("ukey_%s_%s", cleanTableName, columnName),
 						models.UniqueConstraint,
 					)
 					uniqueConstraint.Schema = schemaName
@@ -652,8 +654,8 @@ 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
-						constraint.Name = fmt.Sprintf("fk_%s", constraint.Columns[0])
+						// Generate constraint name based on table and columns
+						constraint.Name = fmt.Sprintf("fk_%s_%s", constraint.Table, strings.Join(constraint.Columns, "_"))
 					}
 				}
 			}
@@ -737,7 +739,11 @@ 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
@@ -797,10 +803,10 @@ func (r *Reader) parseRef(refStr string) *models.Constraint {
 		return nil
 	}
 
-	// Generate short constraint name based on the source column
-	constraintName := fmt.Sprintf("fk_%s_%s", fromTable, toTable)
-	if len(fromColumns) > 0 {
-		constraintName = fmt.Sprintf("fk_%s", fromColumns[0])
+	// Generate constraint name based on table and columns
+	constraintName := fmt.Sprintf("fk_%s_%s", fromTable, strings.Join(fromColumns, "_"))
+	if len(fromColumns) == 0 {
+		constraintName = fmt.Sprintf("fk_%s_%s", fromTable, toTable)
 	}
 
 	constraint := models.InitConstraint(

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: ukey_table_column
+	if _, exists := usersTable.Constraints["ukey_users_email"]; !exists {
+		t.Error("Expected unique constraint 'ukey_users_email' not found")
+		t.Logf("Available constraints: %v", getKeys(usersTable.Constraints))
+	}
+
+	if _, exists := postsTable.Constraints["ukey_posts_slug"]; !exists {
+		t.Error("Expected unique constraint 'ukey_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/migration_writer_test.go

@@ -215,3 +215,70 @@ func TestTemplateExecutor_AuditFunction(t *testing.T) {
 		t.Error("SQL missing DELETE handling")
 	}
 }
+
+func TestWriteMigration_NumericConstraintNames(t *testing.T) {
+	// Current database (empty)
+	current := models.InitDatabase("testdb")
+	currentSchema := models.InitSchema("entity")
+	current.Schemas = append(current.Schemas, currentSchema)
+
+	// Model database (with constraint starting with number)
+	model := models.InitDatabase("testdb")
+	modelSchema := models.InitSchema("entity")
+
+	// Create individual_actor_relationship table
+	table := models.InitTable("individual_actor_relationship", "entity")
+	idCol := models.InitColumn("id", "individual_actor_relationship", "entity")
+	idCol.Type = "integer"
+	idCol.IsPrimaryKey = true
+	table.Columns["id"] = idCol
+
+	actorIDCol := models.InitColumn("actor_id", "individual_actor_relationship", "entity")
+	actorIDCol.Type = "integer"
+	table.Columns["actor_id"] = actorIDCol
+
+	// Add constraint with name starting with number
+	constraint := &models.Constraint{
+		Name:              "215162_fk_actor",
+		Type:              models.ForeignKeyConstraint,
+		Columns:           []string{"actor_id"},
+		ReferencedSchema:  "entity",
+		ReferencedTable:   "actor",
+		ReferencedColumns: []string{"id"},
+		OnDelete:          "CASCADE",
+		OnUpdate:          "NO ACTION",
+	}
+	table.Constraints["215162_fk_actor"] = constraint
+
+	modelSchema.Tables = append(modelSchema.Tables, table)
+	model.Schemas = append(model.Schemas, modelSchema)
+
+	// Generate migration
+	var buf bytes.Buffer
+	writer, err := NewMigrationWriter(&writers.WriterOptions{})
+	if err != nil {
+		t.Fatalf("Failed to create writer: %v", err)
+	}
+	writer.writer = &buf
+
+	err = writer.WriteMigration(model, current)
+	if err != nil {
+		t.Fatalf("WriteMigration failed: %v", err)
+	}
+
+	output := buf.String()
+	t.Logf("Generated migration:\n%s", output)
+
+	// Verify constraint name is properly quoted
+	if !strings.Contains(output, `"215162_fk_actor"`) {
+		t.Error("Constraint name starting with number should be quoted")
+	}
+
+	// Verify the SQL is syntactically correct (contains required keywords)
+	if !strings.Contains(output, "ADD CONSTRAINT") {
+		t.Error("Migration missing ADD CONSTRAINT")
+	}
+	if !strings.Contains(output, "FOREIGN KEY") {
+		t.Error("Migration missing FOREIGN KEY")
+	}
+}

pkg/writers/pgsql/template_functions.go

@@ -21,6 +21,7 @@ func TemplateFunctions() map[string]interface{} {
 		"quote":           quote,
 		"escape":          escape,
 		"safe_identifier": safeIdentifier,
+		"quote_ident":     quoteIdent,
 
 		// Type conversion
 		"goTypeToSQL": goTypeToSQL,
@@ -122,6 +123,43 @@ func safeIdentifier(s string) string {
 	return strings.ToLower(safe)
 }
 
+// quoteIdent quotes a PostgreSQL identifier if necessary
+// Identifiers need quoting if they:
+// - Start with a digit
+// - Contain special characters
+// - Are reserved keywords
+// - Contain uppercase letters (to preserve case)
+func quoteIdent(s string) string {
+	if s == "" {
+		return `""`
+	}
+
+	// Check if quoting is needed
+	needsQuoting := unicode.IsDigit(rune(s[0]))
+
+	// Starts with digit
+
+	// Contains uppercase letters or special characters
+	for _, r := range s {
+		if unicode.IsUpper(r) {
+			needsQuoting = true
+			break
+		}
+		if !unicode.IsLetter(r) && !unicode.IsDigit(r) && r != '_' {
+			needsQuoting = true
+			break
+		}
+	}
+
+	if needsQuoting {
+		// Escape double quotes by doubling them
+		escaped := strings.ReplaceAll(s, `"`, `""`)
+		return `"` + escaped + `"`
+	}
+
+	return s
+}
+
 // Type conversion functions
 
 // goTypeToSQL converts Go type to PostgreSQL type

pkg/writers/pgsql/template_functions_test.go

@@ -101,6 +101,31 @@ func TestSafeIdentifier(t *testing.T) {
 	}
 }
 
+func TestQuoteIdent(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{"valid_name", "valid_name"},
+		{"ValidName", `"ValidName"`},
+		{"123column", `"123column"`},
+		{"215162_fk_constraint", `"215162_fk_constraint"`},
+		{"user-id", `"user-id"`},
+		{"user@domain", `"user@domain"`},
+		{`"quoted"`, `"""quoted"""`},
+		{"", `""`},
+		{"lowercase", "lowercase"},
+		{"with_underscore", "with_underscore"},
+	}
+
+	for _, tt := range tests {
+		result := quoteIdent(tt.input)
+		if result != tt.expected {
+			t.Errorf("quoteIdent(%q) = %q, want %q", tt.input, result, tt.expected)
+		}
+	}
+}
+
 func TestGoTypeToSQL(t *testing.T) {
 	tests := []struct {
 		input    string
@@ -243,7 +268,7 @@ func TestTemplateFunctions(t *testing.T) {
 	// Check that all expected functions are registered
 	expectedFuncs := []string{
 		"upper", "lower", "snake_case", "camelCase",
-		"indent", "quote", "escape", "safe_identifier",
+		"indent", "quote", "escape", "safe_identifier", "quote_ident",
 		"goTypeToSQL", "sqlTypeToGo", "isNumeric", "isText",
 		"first", "last", "filter", "mapFunc", "join_with",
 		"join",

pkg/writers/pgsql/templates.go

@@ -177,6 +177,72 @@ type AuditTriggerData struct {
 	Events       string
 }
 
+// CreateUniqueConstraintData contains data for create unique constraint template
+type CreateUniqueConstraintData struct {
+	SchemaName     string
+	TableName      string
+	ConstraintName string
+	Columns        string
+}
+
+// CreateCheckConstraintData contains data for create check constraint template
+type CreateCheckConstraintData struct {
+	SchemaName     string
+	TableName      string
+	ConstraintName string
+	Expression     string
+}
+
+// CreateForeignKeyWithCheckData contains data for create foreign key with existence check template
+type CreateForeignKeyWithCheckData struct {
+	SchemaName     string
+	TableName      string
+	ConstraintName string
+	SourceColumns  string
+	TargetSchema   string
+	TargetTable    string
+	TargetColumns  string
+	OnDelete       string
+	OnUpdate       string
+	Deferrable     bool
+}
+
+// SetSequenceValueData contains data for set sequence value template
+type SetSequenceValueData struct {
+	SchemaName   string
+	TableName    string
+	SequenceName string
+	ColumnName   string
+}
+
+// CreateSequenceData contains data for create sequence template
+type CreateSequenceData struct {
+	SchemaName   string
+	SequenceName string
+	Increment    int
+	MinValue     int64
+	MaxValue     int64
+	StartValue   int64
+	CacheSize    int
+}
+
+// AddColumnWithCheckData contains data for add column with existence check template
+type AddColumnWithCheckData struct {
+	SchemaName       string
+	TableName        string
+	ColumnName       string
+	ColumnDefinition string
+}
+
+// CreatePrimaryKeyWithAutoGenCheckData contains data for primary key with auto-generated key check template
+type CreatePrimaryKeyWithAutoGenCheckData struct {
+	SchemaName     string
+	TableName      string
+	ConstraintName string
+	AutoGenNames   string // Comma-separated list of names like "'name1', 'name2'"
+	Columns        string
+}
+
 // Execute methods for each template
 
 // ExecuteCreateTable executes the create table template
@@ -319,6 +385,76 @@ func (te *TemplateExecutor) ExecuteAuditTrigger(data AuditTriggerData) (string,
 	return buf.String(), nil
 }
 
+// ExecuteCreateUniqueConstraint executes the create unique constraint template
+func (te *TemplateExecutor) ExecuteCreateUniqueConstraint(data CreateUniqueConstraintData) (string, error) {
+	var buf bytes.Buffer
+	err := te.templates.ExecuteTemplate(&buf, "create_unique_constraint.tmpl", data)
+	if err != nil {
+		return "", fmt.Errorf("failed to execute create_unique_constraint template: %w", err)
+	}
+	return buf.String(), nil
+}
+
+// ExecuteCreateCheckConstraint executes the create check constraint template
+func (te *TemplateExecutor) ExecuteCreateCheckConstraint(data CreateCheckConstraintData) (string, error) {
+	var buf bytes.Buffer
+	err := te.templates.ExecuteTemplate(&buf, "create_check_constraint.tmpl", data)
+	if err != nil {
+		return "", fmt.Errorf("failed to execute create_check_constraint template: %w", err)
+	}
+	return buf.String(), nil
+}
+
+// ExecuteCreateForeignKeyWithCheck executes the create foreign key with check template
+func (te *TemplateExecutor) ExecuteCreateForeignKeyWithCheck(data CreateForeignKeyWithCheckData) (string, error) {
+	var buf bytes.Buffer
+	err := te.templates.ExecuteTemplate(&buf, "create_foreign_key_with_check.tmpl", data)
+	if err != nil {
+		return "", fmt.Errorf("failed to execute create_foreign_key_with_check template: %w", err)
+	}
+	return buf.String(), nil
+}
+
+// ExecuteSetSequenceValue executes the set sequence value template
+func (te *TemplateExecutor) ExecuteSetSequenceValue(data SetSequenceValueData) (string, error) {
+	var buf bytes.Buffer
+	err := te.templates.ExecuteTemplate(&buf, "set_sequence_value.tmpl", data)
+	if err != nil {
+		return "", fmt.Errorf("failed to execute set_sequence_value template: %w", err)
+	}
+	return buf.String(), nil
+}
+
+// ExecuteCreateSequence executes the create sequence template
+func (te *TemplateExecutor) ExecuteCreateSequence(data CreateSequenceData) (string, error) {
+	var buf bytes.Buffer
+	err := te.templates.ExecuteTemplate(&buf, "create_sequence.tmpl", data)
+	if err != nil {
+		return "", fmt.Errorf("failed to execute create_sequence template: %w", err)
+	}
+	return buf.String(), nil
+}
+
+// ExecuteAddColumnWithCheck executes the add column with check template
+func (te *TemplateExecutor) ExecuteAddColumnWithCheck(data AddColumnWithCheckData) (string, error) {
+	var buf bytes.Buffer
+	err := te.templates.ExecuteTemplate(&buf, "add_column_with_check.tmpl", data)
+	if err != nil {
+		return "", fmt.Errorf("failed to execute add_column_with_check template: %w", err)
+	}
+	return buf.String(), nil
+}
+
+// ExecuteCreatePrimaryKeyWithAutoGenCheck executes the create primary key with auto-generated key check template
+func (te *TemplateExecutor) ExecuteCreatePrimaryKeyWithAutoGenCheck(data CreatePrimaryKeyWithAutoGenCheckData) (string, error) {
+	var buf bytes.Buffer
+	err := te.templates.ExecuteTemplate(&buf, "create_primary_key_with_autogen_check.tmpl", data)
+	if err != nil {
+		return "", fmt.Errorf("failed to execute create_primary_key_with_autogen_check template: %w", err)
+	}
+	return buf.String(), nil
+}
+
 // Helper functions to build template data from models
 
 // BuildCreateTableData builds CreateTableData from a models.Table

pkg/writers/pgsql/templates/add_column.tmpl

@@ -1,4 +1,4 @@
-ALTER TABLE {{.SchemaName}}.{{.TableName}}
-  ADD COLUMN IF NOT EXISTS {{.ColumnName}} {{.ColumnType}}
+ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}}
+  ADD COLUMN IF NOT EXISTS {{quote_ident .ColumnName}} {{.ColumnType}}
 {{- if .Default}} DEFAULT {{.Default}}{{end}}
 {{- if .NotNull}} NOT NULL{{end}};

pkg/writers/pgsql/templates/add_column_with_check.tmpl

@@ -0,0 +1,12 @@
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM information_schema.columns
+    WHERE table_schema = '{{.SchemaName}}'
+      AND table_name = '{{.TableName}}'
+      AND column_name = '{{.ColumnName}}'
+  ) THEN
+    ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}} ADD COLUMN {{.ColumnDefinition}};
+  END IF;
+END;
+$$;

pkg/writers/pgsql/templates/alter_column_default.tmpl

@@ -1,7 +1,7 @@
 {{- if .SetDefault -}}
-ALTER TABLE {{.SchemaName}}.{{.TableName}}
-  ALTER COLUMN {{.ColumnName}} SET DEFAULT {{.DefaultValue}};
+ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}}
+  ALTER COLUMN {{quote_ident .ColumnName}} SET DEFAULT {{.DefaultValue}};
 {{- else -}}
-ALTER TABLE {{.SchemaName}}.{{.TableName}}
-  ALTER COLUMN {{.ColumnName}} DROP DEFAULT;
+ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}}
+  ALTER COLUMN {{quote_ident .ColumnName}} DROP DEFAULT;
 {{- end -}}

pkg/writers/pgsql/templates/alter_column_type.tmpl

@@ -1,2 +1,2 @@
-ALTER TABLE {{.SchemaName}}.{{.TableName}}
-  ALTER COLUMN {{.ColumnName}} TYPE {{.NewType}};
+ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}}
+  ALTER COLUMN {{quote_ident .ColumnName}} TYPE {{.NewType}};

pkg/writers/pgsql/templates/comment_column.tmpl

@@ -1 +1 @@
-COMMENT ON COLUMN {{.SchemaName}}.{{.TableName}}.{{.ColumnName}} IS '{{.Comment}}';
+COMMENT ON COLUMN {{quote_ident .SchemaName}}.{{quote_ident .TableName}}.{{quote_ident .ColumnName}} IS '{{.Comment}}';

pkg/writers/pgsql/templates/comment_table.tmpl

@@ -1 +1 @@
-COMMENT ON TABLE {{.SchemaName}}.{{.TableName}} IS '{{.Comment}}';
+COMMENT ON TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}} IS '{{.Comment}}';

pkg/writers/pgsql/templates/create_check_constraint.tmpl

@@ -0,0 +1,12 @@
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM information_schema.table_constraints
+    WHERE table_schema = '{{.SchemaName}}'
+      AND table_name = '{{.TableName}}'
+      AND constraint_name = '{{.ConstraintName}}'
+  ) THEN
+    ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}} ADD CONSTRAINT {{quote_ident .ConstraintName}} CHECK ({{.Expression}});
+  END IF;
+END;
+$$;

pkg/writers/pgsql/templates/create_foreign_key.tmpl

@@ -1,10 +1,10 @@
-ALTER TABLE {{.SchemaName}}.{{.TableName}}
-  DROP CONSTRAINT IF EXISTS {{.ConstraintName}};
+ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}}
+  DROP CONSTRAINT IF EXISTS {{quote_ident .ConstraintName}};
 
-ALTER TABLE {{.SchemaName}}.{{.TableName}}
-  ADD CONSTRAINT {{.ConstraintName}}
+ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}}
+  ADD CONSTRAINT {{quote_ident .ConstraintName}}
   FOREIGN KEY ({{.SourceColumns}})
-  REFERENCES {{.TargetSchema}}.{{.TargetTable}} ({{.TargetColumns}})
+  REFERENCES {{quote_ident .TargetSchema}}.{{quote_ident .TargetTable}} ({{.TargetColumns}})
   ON DELETE {{.OnDelete}}
   ON UPDATE {{.OnUpdate}}
   DEFERRABLE;

pkg/writers/pgsql/templates/create_foreign_key_with_check.tmpl

@@ -0,0 +1,18 @@
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM information_schema.table_constraints
+    WHERE table_schema = '{{.SchemaName}}'
+      AND table_name = '{{.TableName}}'
+      AND constraint_name = '{{.ConstraintName}}'
+  ) THEN
+    ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}}
+      ADD CONSTRAINT {{quote_ident .ConstraintName}}
+      FOREIGN KEY ({{.SourceColumns}})
+      REFERENCES {{quote_ident .TargetSchema}}.{{quote_ident .TargetTable}} ({{.TargetColumns}})
+      ON DELETE {{.OnDelete}}
+      ON UPDATE {{.OnUpdate}}{{if .Deferrable}}
+      DEFERRABLE{{end}};
+  END IF;
+END;
+$$;

pkg/writers/pgsql/templates/create_index.tmpl

@@ -1,2 +1,2 @@
-CREATE {{if .Unique}}UNIQUE {{end}}INDEX IF NOT EXISTS {{.IndexName}}
-  ON {{.SchemaName}}.{{.TableName}} USING {{.IndexType}} ({{.Columns}});
+CREATE {{if .Unique}}UNIQUE {{end}}INDEX IF NOT EXISTS {{quote_ident .IndexName}}
+  ON {{quote_ident .SchemaName}}.{{quote_ident .TableName}} USING {{.IndexType}} ({{.Columns}});

pkg/writers/pgsql/templates/create_primary_key.tmpl

@@ -6,8 +6,8 @@ BEGIN
       AND table_name = '{{.TableName}}'
       AND constraint_name = '{{.ConstraintName}}'
   ) THEN
-    ALTER TABLE {{.SchemaName}}.{{.TableName}}
-      ADD CONSTRAINT {{.ConstraintName}} PRIMARY KEY ({{.Columns}});
+    ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}}
+      ADD CONSTRAINT {{quote_ident .ConstraintName}} PRIMARY KEY ({{.Columns}});
   END IF;
 END;
 $$;

pkg/writers/pgsql/templates/create_primary_key_with_autogen_check.tmpl

@@ -0,0 +1,27 @@
+DO $$
+DECLARE
+  auto_pk_name text;
+BEGIN
+  -- Drop auto-generated primary key if it exists
+  SELECT constraint_name INTO auto_pk_name
+  FROM information_schema.table_constraints
+  WHERE table_schema = '{{.SchemaName}}'
+    AND table_name = '{{.TableName}}'
+    AND constraint_type = 'PRIMARY KEY'
+    AND constraint_name IN ({{.AutoGenNames}});
+
+  IF auto_pk_name IS NOT NULL THEN
+    EXECUTE 'ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}} DROP CONSTRAINT ' || quote_ident(auto_pk_name);
+  END IF;
+
+  -- Add named primary key if it doesn't exist
+  IF NOT EXISTS (
+    SELECT 1 FROM information_schema.table_constraints
+    WHERE table_schema = '{{.SchemaName}}'
+      AND table_name = '{{.TableName}}'
+      AND constraint_name = '{{.ConstraintName}}'
+  ) THEN
+    ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}} ADD CONSTRAINT {{quote_ident .ConstraintName}} PRIMARY KEY ({{.Columns}});
+  END IF;
+END;
+$$;

pkg/writers/pgsql/templates/create_sequence.tmpl

@@ -0,0 +1,6 @@
+CREATE SEQUENCE IF NOT EXISTS {{quote_ident .SchemaName}}.{{quote_ident .SequenceName}}
+  INCREMENT {{.Increment}}
+  MINVALUE {{.MinValue}}
+  MAXVALUE {{.MaxValue}}
+  START {{.StartValue}}
+  CACHE {{.CacheSize}};

pkg/writers/pgsql/templates/create_table.tmpl

@@ -1,7 +1,7 @@
-CREATE TABLE IF NOT EXISTS {{.SchemaName}}.{{.TableName}} (
+CREATE TABLE IF NOT EXISTS {{quote_ident .SchemaName}}.{{quote_ident .TableName}} (
 {{- range $i, $col := .Columns}}
 {{- if $i}},{{end}}
-  {{$col.Name}} {{$col.Type}}
+  {{quote_ident $col.Name}} {{$col.Type}}
 {{- if $col.Default}} DEFAULT {{$col.Default}}{{end}}
 {{- if $col.NotNull}} NOT NULL{{end}}
 {{- end}}

pkg/writers/pgsql/templates/create_unique_constraint.tmpl

@@ -0,0 +1,12 @@
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM information_schema.table_constraints
+    WHERE table_schema = '{{.SchemaName}}'
+      AND table_name = '{{.TableName}}'
+      AND constraint_name = '{{.ConstraintName}}'
+  ) THEN
+    ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}} ADD CONSTRAINT {{quote_ident .ConstraintName}} UNIQUE ({{.Columns}});
+  END IF;
+END;
+$$;

pkg/writers/pgsql/templates/drop_constraint.tmpl

@@ -1 +1 @@
-ALTER TABLE {{.SchemaName}}.{{.TableName}} DROP CONSTRAINT IF EXISTS {{.ConstraintName}};
+ALTER TABLE {{quote_ident .SchemaName}}.{{quote_ident .TableName}} DROP CONSTRAINT IF EXISTS {{quote_ident .ConstraintName}};

pkg/writers/pgsql/templates/drop_index.tmpl

@@ -1 +1 @@
-DROP INDEX IF EXISTS {{.SchemaName}}.{{.IndexName}} CASCADE;
+DROP INDEX IF EXISTS {{quote_ident .SchemaName}}.{{quote_ident .IndexName}} CASCADE;

pkg/writers/pgsql/templates/set_sequence_value.tmpl

@@ -0,0 +1,19 @@
+DO $$
+DECLARE
+  m_cnt bigint;
+BEGIN
+  IF EXISTS (
+    SELECT 1 FROM pg_class c
+    INNER JOIN pg_namespace n ON n.oid = c.relnamespace
+    WHERE c.relname = '{{.SequenceName}}'
+      AND n.nspname = '{{.SchemaName}}'
+      AND c.relkind = 'S'
+  ) THEN
+    SELECT COALESCE(MAX({{quote_ident .ColumnName}}), 0) + 1
+    FROM {{quote_ident .SchemaName}}.{{quote_ident .TableName}}
+    INTO m_cnt;
+    
+    PERFORM setval('{{quote_ident .SchemaName}}.{{quote_ident .SequenceName}}'::regclass, m_cnt);
+  END IF;
+END;
+$$;

pkg/writers/pgsql/writer.go

@@ -22,6 +22,7 @@ type Writer struct {
 	options         *writers.WriterOptions
 	writer          io.Writer
 	executionReport *ExecutionReport
+	executor        *TemplateExecutor
 }
 
 // ExecutionReport tracks the execution status of SQL statements
@@ -57,8 +58,10 @@ type ExecutionError struct {
 
 // NewWriter creates a new PostgreSQL SQL writer
 func NewWriter(options *writers.WriterOptions) *Writer {
+	executor, _ := NewTemplateExecutor()
 	return &Writer{
 		options:  options,
+		executor: executor,
 	}
 }
 
@@ -215,36 +218,19 @@ func (w *Writer) GenerateSchemaStatements(schema *models.Schema) ([]string, erro
 				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, ", "))
+			// Use template to generate primary key statement
+			data := CreatePrimaryKeyWithAutoGenCheckData{
+				SchemaName:     schema.Name,
+				TableName:      table.Name,
+				ConstraintName: pkName,
+				AutoGenNames:   formatStringList(autoGenPKNames),
+				Columns:        strings.Join(pkColumns, ", "),
+			}
+
+			stmt, err := w.executor.ExecuteCreatePrimaryKeyWithAutoGenCheck(data)
+			if err != nil {
+				return nil, fmt.Errorf("failed to generate primary key for %s.%s: %w", schema.Name, table.Name, err)
+			}
 			statements = append(statements, stmt)
 		}
 	}
@@ -290,7 +276,53 @@ func (w *Writer) GenerateSchemaStatements(schema *models.Schema) ([]string, erro
 			}
 
 			stmt := fmt.Sprintf("CREATE %sINDEX IF NOT EXISTS %s ON %s.%s USING %s (%s)%s",
-				uniqueStr, index.Name, schema.SQLName(), table.SQLName(), indexType, strings.Join(columnExprs, ", "), whereClause)
+				uniqueStr, quoteIdentifier(index.Name), schema.SQLName(), table.SQLName(), indexType, strings.Join(columnExprs, ", "), whereClause)
+			statements = append(statements, stmt)
+		}
+	}
+
+	// Phase 5.5: Unique constraints
+	for _, table := range schema.Tables {
+		for _, constraint := range table.Constraints {
+			if constraint.Type != models.UniqueConstraint {
+				continue
+			}
+
+			// Use template to generate unique constraint statement
+			data := CreateUniqueConstraintData{
+				SchemaName:     schema.Name,
+				TableName:      table.Name,
+				ConstraintName: constraint.Name,
+				Columns:        strings.Join(constraint.Columns, ", "),
+			}
+
+			stmt, err := w.executor.ExecuteCreateUniqueConstraint(data)
+			if err != nil {
+				return nil, fmt.Errorf("failed to generate unique constraint for %s.%s: %w", schema.Name, table.Name, err)
+			}
+			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
+			}
+
+			// Use template to generate check constraint statement
+			data := CreateCheckConstraintData{
+				SchemaName:     schema.Name,
+				TableName:      table.Name,
+				ConstraintName: constraint.Name,
+				Expression:     constraint.Expression,
+			}
+
+			stmt, err := w.executor.ExecuteCreateCheckConstraint(data)
+			if err != nil {
+				return nil, fmt.Errorf("failed to generate check constraint for %s.%s: %w", schema.Name, table.Name, err)
+			}
 			statements = append(statements, stmt)
 		}
 	}
@@ -317,23 +349,24 @@ func (w *Writer) GenerateSchemaStatements(schema *models.Schema) ([]string, erro
 				onUpdate = "NO ACTION"
 			}
 
-			// 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),
-				strings.Join(constraint.ReferencedColumns, ", "),
-				onDelete, onUpdate)
+			// Use template to generate foreign key statement
+			data := CreateForeignKeyWithCheckData{
+				SchemaName:     schema.Name,
+				TableName:      table.Name,
+				ConstraintName: constraint.Name,
+				SourceColumns:  strings.Join(constraint.Columns, ", "),
+				TargetSchema:   refSchema,
+				TargetTable:    constraint.ReferencedTable,
+				TargetColumns:  strings.Join(constraint.ReferencedColumns, ", "),
+				OnDelete:       onDelete,
+				OnUpdate:       onUpdate,
+				Deferrable:     false,
+			}
+
+			stmt, err := w.executor.ExecuteCreateForeignKeyWithCheck(data)
+			if err != nil {
+				return nil, fmt.Errorf("failed to generate foreign key for %s.%s: %w", schema.Name, table.Name, err)
+			}
 			statements = append(statements, stmt)
 		}
 	}
@@ -381,19 +414,18 @@ func (w *Writer) GenerateAddColumnStatements(schema *models.Schema) ([]string, e
 		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)
+			// Use template to generate add column statement
+			data := AddColumnWithCheckData{
+				SchemaName:       schema.Name,
+				TableName:        table.Name,
+				ColumnName:       col.Name,
+				ColumnDefinition: colDef,
+			}
+
+			stmt, err := w.executor.ExecuteAddColumnWithCheck(data)
+			if err != nil {
+				return nil, fmt.Errorf("failed to generate add column for %s.%s.%s: %w", schema.Name, table.Name, col.Name, err)
+			}
 			statements = append(statements, stmt)
 		}
 	}
@@ -542,6 +574,16 @@ 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
@@ -639,13 +681,23 @@ func (w *Writer) writeSequences(schema *models.Schema) error {
 		}
 
 		seqName := fmt.Sprintf("identity_%s_%s", table.SQLName(), pk.SQLName())
-		fmt.Fprintf(w.writer, "CREATE SEQUENCE IF NOT EXISTS %s.%s\n",
-			schema.SQLName(), seqName)
-		fmt.Fprintf(w.writer, "  INCREMENT 1\n")
-		fmt.Fprintf(w.writer, "  MINVALUE 1\n")
-		fmt.Fprintf(w.writer, "  MAXVALUE 9223372036854775807\n")
-		fmt.Fprintf(w.writer, "  START 1\n")
-		fmt.Fprintf(w.writer, "  CACHE 1;\n\n")
+
+		data := CreateSequenceData{
+			SchemaName:   schema.Name,
+			SequenceName: seqName,
+			Increment:    1,
+			MinValue:     1,
+			MaxValue:     9223372036854775807,
+			StartValue:   1,
+			CacheSize:    1,
+		}
+
+		sql, err := w.executor.ExecuteCreateSequence(data)
+		if err != nil {
+			return fmt.Errorf("failed to generate create sequence for %s.%s: %w", schema.Name, seqName, err)
+		}
+		fmt.Fprint(w.writer, sql)
+		fmt.Fprint(w.writer, "\n")
 	}
 
 	return nil
@@ -687,18 +739,19 @@ func (w *Writer) writeAddColumns(schema *models.Schema) error {
 		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")
+			data := AddColumnWithCheckData{
+				SchemaName:       schema.Name,
+				TableName:        table.Name,
+				ColumnName:       col.Name,
+				ColumnDefinition: colDef,
+			}
+
+			sql, err := w.executor.ExecuteAddColumnWithCheck(data)
+			if err != nil {
+				return fmt.Errorf("failed to generate add column for %s.%s.%s: %w", schema.Name, table.Name, col.Name, err)
+			}
+			fmt.Fprint(w.writer, sql)
+			fmt.Fprint(w.writer, "\n")
 		}
 	}
 
@@ -752,37 +805,20 @@ func (w *Writer) writePrimaryKeys(schema *models.Schema) error {
 			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")
+		data := CreatePrimaryKeyWithAutoGenCheckData{
+			SchemaName:     schema.Name,
+			TableName:      table.Name,
+			ConstraintName: pkName,
+			AutoGenNames:   formatStringList(autoGenPKNames),
+			Columns:        strings.Join(columnNames, ", "),
+		}
 
-		// 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)
-		fmt.Fprintf(w.writer, "      AND table_name = '%s'\n", table.Name)
-		fmt.Fprintf(w.writer, "      AND constraint_name = '%s'\n", pkName)
-		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 PRIMARY KEY (%s);\n",
-			pkName, strings.Join(columnNames, ", "))
-		fmt.Fprintf(w.writer, "  END IF;\n")
-		fmt.Fprintf(w.writer, "END;\n$$;\n\n")
+		sql, err := w.executor.ExecuteCreatePrimaryKeyWithAutoGenCheck(data)
+		if err != nil {
+			return fmt.Errorf("failed to generate primary key for %s.%s: %w", schema.Name, table.Name, err)
+		}
+		fmt.Fprint(w.writer, sql)
+		fmt.Fprint(w.writer, "\n")
 	}
 
 	return nil
@@ -865,6 +901,91 @@ 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
+			}
+
+			sql, err := w.executor.ExecuteCreateUniqueConstraint(CreateUniqueConstraintData{
+				SchemaName:     schema.Name,
+				TableName:      table.Name,
+				ConstraintName: constraint.Name,
+				Columns:        strings.Join(columnExprs, ", "),
+			})
+			if err != nil {
+				return fmt.Errorf("failed to generate unique constraint: %w", err)
+			}
+
+			fmt.Fprintf(w.writer, "%s\n\n", sql)
+		}
+	}
+
+	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
+			}
+
+			sql, err := w.executor.ExecuteCreateCheckConstraint(CreateCheckConstraintData{
+				SchemaName:     schema.Name,
+				TableName:      table.Name,
+				ConstraintName: constraint.Name,
+				Expression:     constraint.Expression,
+			})
+			if err != nil {
+				return fmt.Errorf("failed to generate check constraint: %w", err)
+			}
+
+			fmt.Fprintf(w.writer, "%s\n\n", sql)
+		}
+	}
+
+	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)
@@ -942,24 +1063,103 @@ func (w *Writer) writeForeignKeys(schema *models.Schema) error {
 				refTable = rel.ToTable
 			}
 
-			// Use DO block to check if constraint exists before adding
-			fmt.Fprintf(w.writer, "DO $$\nBEGIN\n")
-			fmt.Fprintf(w.writer, "  IF NOT EXISTS (\n")
-			fmt.Fprintf(w.writer, "    SELECT 1 FROM information_schema.table_constraints\n")
-			fmt.Fprintf(w.writer, "    WHERE table_schema = '%s'\n", schema.Name)
-			fmt.Fprintf(w.writer, "      AND table_name = '%s'\n", table.Name)
-			fmt.Fprintf(w.writer, "      AND constraint_name = '%s'\n", fkName)
-			fmt.Fprintf(w.writer, "  ) THEN\n")
-			fmt.Fprintf(w.writer, "    ALTER TABLE %s.%s\n", schema.SQLName(), table.SQLName())
-			fmt.Fprintf(w.writer, "      ADD CONSTRAINT %s\n", fkName)
-			fmt.Fprintf(w.writer, "      FOREIGN KEY (%s)\n", strings.Join(sourceColumns, ", "))
-			fmt.Fprintf(w.writer, "      REFERENCES %s.%s (%s)\n",
-				refSchema, refTable, strings.Join(targetColumns, ", "))
-			fmt.Fprintf(w.writer, "      ON DELETE %s\n", onDelete)
-			fmt.Fprintf(w.writer, "      ON UPDATE %s\n", onUpdate)
-			fmt.Fprintf(w.writer, "      DEFERRABLE;\n")
-			fmt.Fprintf(w.writer, "  END IF;\n")
-			fmt.Fprintf(w.writer, "END;\n$$;\n\n")
+			// Use template executor to generate foreign key with existence check
+			data := CreateForeignKeyWithCheckData{
+				SchemaName:     schema.Name,
+				TableName:      table.Name,
+				ConstraintName: fkName,
+				SourceColumns:  strings.Join(sourceColumns, ", "),
+				TargetSchema:   refSchema,
+				TargetTable:    refTable,
+				TargetColumns:  strings.Join(targetColumns, ", "),
+				OnDelete:       onDelete,
+				OnUpdate:       onUpdate,
+				Deferrable:     true,
+			}
+			sql, err := w.executor.ExecuteCreateForeignKeyWithCheck(data)
+			if err != nil {
+				return fmt.Errorf("failed to generate foreign key for %s.%s: %w", schema.Name, table.Name, err)
+			}
+			fmt.Fprint(w.writer, sql)
+		}
+
+		// 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 template executor to generate foreign key with existence check
+			data := CreateForeignKeyWithCheckData{
+				SchemaName:     schema.Name,
+				TableName:      table.Name,
+				ConstraintName: constraint.Name,
+				SourceColumns:  strings.Join(sourceColumns, ", "),
+				TargetSchema:   refSchema,
+				TargetTable:    refTable,
+				TargetColumns:  strings.Join(targetColumns, ", "),
+				OnDelete:       onDelete,
+				OnUpdate:       onUpdate,
+				Deferrable:     false,
+			}
+			sql, err := w.executor.ExecuteCreateForeignKeyWithCheck(data)
+			if err != nil {
+				return fmt.Errorf("failed to generate foreign key for %s.%s: %w", schema.Name, table.Name, err)
+			}
+			fmt.Fprint(w.writer, sql)
 		}
 	}
 
@@ -978,26 +1178,19 @@ func (w *Writer) writeSetSequenceValues(schema *models.Schema) error {
 
 		seqName := fmt.Sprintf("identity_%s_%s", table.SQLName(), pk.SQLName())
 
-		fmt.Fprintf(w.writer, "DO $$\n")
-		fmt.Fprintf(w.writer, "DECLARE\n")
-		fmt.Fprintf(w.writer, "  m_cnt bigint;\n")
-		fmt.Fprintf(w.writer, "BEGIN\n")
-		fmt.Fprintf(w.writer, "  IF EXISTS (\n")
-		fmt.Fprintf(w.writer, "    SELECT 1 FROM pg_class c\n")
-		fmt.Fprintf(w.writer, "    INNER JOIN pg_namespace n ON n.oid = c.relnamespace\n")
-		fmt.Fprintf(w.writer, "    WHERE c.relname = '%s'\n", seqName)
-		fmt.Fprintf(w.writer, "      AND n.nspname = '%s'\n", schema.Name)
-		fmt.Fprintf(w.writer, "      AND c.relkind = 'S'\n")
-		fmt.Fprintf(w.writer, "  ) THEN\n")
-		fmt.Fprintf(w.writer, "    SELECT COALESCE(MAX(%s), 0) + 1\n", pk.SQLName())
-		fmt.Fprintf(w.writer, "    FROM %s.%s\n", schema.SQLName(), table.SQLName())
-		fmt.Fprintf(w.writer, "    INTO m_cnt;\n")
-		fmt.Fprintf(w.writer, "    \n")
-		fmt.Fprintf(w.writer, "    PERFORM setval('%s.%s'::regclass, m_cnt);\n",
-			schema.SQLName(), seqName)
-		fmt.Fprintf(w.writer, "  END IF;\n")
-		fmt.Fprintf(w.writer, "END;\n")
-		fmt.Fprintf(w.writer, "$$;\n\n")
+		// Use template executor to generate set sequence value statement
+		data := SetSequenceValueData{
+			SchemaName:   schema.Name,
+			TableName:    table.Name,
+			SequenceName: seqName,
+			ColumnName:   pk.Name,
+		}
+		sql, err := w.executor.ExecuteSetSequenceValue(data)
+		if err != nil {
+			return fmt.Errorf("failed to generate set sequence value for %s.%s: %w", schema.Name, table.Name, err)
+		}
+		fmt.Fprint(w.writer, sql)
+		fmt.Fprint(w.writer, "\n")
 	}
 
 	return nil
@@ -1217,7 +1410,8 @@ func (w *Writer) executeDatabaseSQL(db *models.Database, connString string) erro
 			continue
 		}
 
-		fmt.Fprintf(os.Stderr, "Executing statement %d/%d...\n", i+1, len(statements))
+		stmtType := detectStatementType(stmtTrimmed)
+		fmt.Fprintf(os.Stderr, "Executing statement %d/%d [%s]...\n", i+1, len(statements), stmtType)
 
 		_, execErr := conn.Exec(ctx, stmt)
 		if execErr != nil {
@@ -1351,3 +1545,94 @@ func truncateStatement(stmt string) string {
 func getCurrentTimestamp() string {
 	return time.Now().Format("2006-01-02 15:04:05")
 }
+
+// detectStatementType detects the type of SQL statement for logging
+func detectStatementType(stmt string) string {
+	upperStmt := strings.ToUpper(stmt)
+
+	// Check for DO blocks (used for conditional DDL)
+	if strings.HasPrefix(upperStmt, "DO $$") || strings.HasPrefix(upperStmt, "DO $") {
+		// Look inside the DO block for the actual operation
+		if strings.Contains(upperStmt, "ALTER TABLE") && strings.Contains(upperStmt, "ADD CONSTRAINT") {
+			if strings.Contains(upperStmt, "UNIQUE") {
+				return "ADD UNIQUE CONSTRAINT"
+			} else if strings.Contains(upperStmt, "FOREIGN KEY") {
+				return "ADD FOREIGN KEY"
+			} else if strings.Contains(upperStmt, "PRIMARY KEY") {
+				return "ADD PRIMARY KEY"
+			} else if strings.Contains(upperStmt, "CHECK") {
+				return "ADD CHECK CONSTRAINT"
+			}
+			return "ADD CONSTRAINT"
+		}
+		if strings.Contains(upperStmt, "ALTER TABLE") && strings.Contains(upperStmt, "ADD COLUMN") {
+			return "ADD COLUMN"
+		}
+		if strings.Contains(upperStmt, "DROP CONSTRAINT") {
+			return "DROP CONSTRAINT"
+		}
+		return "DO BLOCK"
+	}
+
+	// Direct DDL statements
+	if strings.HasPrefix(upperStmt, "CREATE SCHEMA") {
+		return "CREATE SCHEMA"
+	}
+	if strings.HasPrefix(upperStmt, "CREATE SEQUENCE") {
+		return "CREATE SEQUENCE"
+	}
+	if strings.HasPrefix(upperStmt, "CREATE TABLE") {
+		return "CREATE TABLE"
+	}
+	if strings.HasPrefix(upperStmt, "CREATE INDEX") {
+		return "CREATE INDEX"
+	}
+	if strings.HasPrefix(upperStmt, "CREATE UNIQUE INDEX") {
+		return "CREATE UNIQUE INDEX"
+	}
+	if strings.HasPrefix(upperStmt, "ALTER TABLE") {
+		if strings.Contains(upperStmt, "ADD CONSTRAINT") {
+			if strings.Contains(upperStmt, "FOREIGN KEY") {
+				return "ADD FOREIGN KEY"
+			} else if strings.Contains(upperStmt, "PRIMARY KEY") {
+				return "ADD PRIMARY KEY"
+			} else if strings.Contains(upperStmt, "UNIQUE") {
+				return "ADD UNIQUE CONSTRAINT"
+			} else if strings.Contains(upperStmt, "CHECK") {
+				return "ADD CHECK CONSTRAINT"
+			}
+			return "ADD CONSTRAINT"
+		}
+		if strings.Contains(upperStmt, "ADD COLUMN") {
+			return "ADD COLUMN"
+		}
+		if strings.Contains(upperStmt, "DROP CONSTRAINT") {
+			return "DROP CONSTRAINT"
+		}
+		if strings.Contains(upperStmt, "ALTER COLUMN") {
+			return "ALTER COLUMN"
+		}
+		return "ALTER TABLE"
+	}
+	if strings.HasPrefix(upperStmt, "COMMENT ON TABLE") {
+		return "COMMENT ON TABLE"
+	}
+	if strings.HasPrefix(upperStmt, "COMMENT ON COLUMN") {
+		return "COMMENT ON COLUMN"
+	}
+	if strings.HasPrefix(upperStmt, "DROP TABLE") {
+		return "DROP TABLE"
+	}
+	if strings.HasPrefix(upperStmt, "DROP INDEX") {
+		return "DROP INDEX"
+	}
+
+	// Default
+	return "SQL"
+}
+
+// quoteIdentifier wraps an identifier in double quotes if necessary
+// This is needed for identifiers that start with numbers or contain special characters
+func quoteIdentifier(s string) string {
+	return quoteIdent(s)
+}

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")