Add timestamps columns (created_at, updated_at) and triggers (update updated_at on row update) to all user tables in postgreSQL

add_timestamp_triggers.sql

-- add timestamps (created_at, updated_at)
-- add trigger for timestamp updated_at

CREATE OR REPLACE FUNCTION add_custom_timestamps() RETURNS void AS $$
DECLARE
    row_data RECORD;
    -- row_data information_schema.tables%ROWTYPE;
BEGIN

  FOR row_data IN
      SELECT *
      FROM information_schema.tables
      WHERE table_type = 'BASE TABLE'
        AND table_schema = 'public'
        AND table_name NOT LIKE 'pg\_%'
  LOOP

    EXECUTE ' ALTER TABLE '
    	|| row_data.table_name
    	|| ' ADD COLUMN IF NOT EXISTS '
    	|| ' created_at timestamp with time zone NOT NULL DEFAULT now(), '
    	|| ' ADD COLUMN IF NOT EXISTS '
    	|| ' updated_at timestamp with time zone NOT NULL DEFAULT now(); ';

	  EXECUTE ' CREATE TRIGGER update_moddatetime_' || row_data.table_name
     	|| ' BEFORE UPDATE ON '
		|| row_data.table_name
		|| ' FOR EACH ROW'
		|| ' EXECUTE PROCEDURE moddatetime(updated_at); ';

  END LOOP;

END; $$ LANGUAGE PLPGSQL;