feat(pgsql): ✨ Add templates for constraints and sequences

* Introduce new templates for creating unique, check, and foreign key constraints with existence checks.
* Add templates for setting sequence values and creating sequences.
* Refactor existing SQL generation logic to utilize new templates for better maintainability and readability.
* Ensure identifiers are properly quoted to handle special characters and reserved keywords.

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