将记录与postgresql中的先前记录进行比较

CREATE TABLE my_table (
  id SERIAL PRIMARY KEY,
  data TEXT
);

CREATE TABLE my_table_history (
  id SERIAL PRIMARY KEY,
  previous_data TEXT,
  current_data TEXT,
  change_timestamp TIMESTAMP DEFAULT NOW()
);

CREATE OR REPLACE FUNCTION my_table_trigger_function()
RETURNS TRIGGER AS $$
BEGIN
  IF TG_OP = 'UPDATE' THEN
    INSERT INTO my_table_history (previous_data, current_data)
    VALUES (OLD.data, NEW.data);
  ELSIF TG_OP = 'DELETE' THEN
    INSERT INTO my_table_history (previous_data)
    VALUES (OLD.data);
  END IF;
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER my_table_trigger
AFTER INSERT OR UPDATE OR DELETE ON my_table
FOR EACH ROW
EXECUTE FUNCTION my_table_trigger_function();