IntermediateAdvanced PostgreSQL

Triggers: auto-update updated_at timestamp

The query

SQL

-- Step 1: Create trigger function
CREATE OR REPLACE FUNCTION update_modified_column()
RETURNS TRIGGER AS $$
BEGIN
  NEW.updated_at = NOW();
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

-- Step 2: Attach trigger to table
CREATE TRIGGER set_updated_at
  BEFORE UPDATE ON employees
  FOR EACH ROW
  EXECUTE FUNCTION update_modified_column();

Tested against PostgreSQL 16

Note

“Triggers auto-execute functions on INSERT/UPDATE/DELETE. Common uses: audit logs, timestamps, validation.

Tables referenced

employees10 cols