---

name: postgresql-plpgsql description: Write PL/pgSQL - functions, procedures, triggers, error handling version: "3.0.0" sasmp_version: "1.3.0" bonded_agent: 06-postgresql-plpgsql bond_type: PRIMARY_BOND category: database difficulty: advanced estimated_time: 4h

PostgreSQL PL/pgSQL Skill

Atomic skill for procedural programming

Overview

Production-ready patterns for functions, procedures, triggers, and exception handling.

Prerequisites

• PostgreSQL 16+
• Understanding of SQL

Parameters

Copyparameters:
  code_type:
    type: string
    required: true
    enum: [function, procedure, trigger, aggregate]
  volatility:
    type: string
    enum: [IMMUTABLE, STABLE, VOLATILE]

Quick Reference

Function Template

CopyCREATE OR REPLACE FUNCTION func_name(p_param TYPE)
RETURNS return_type
LANGUAGE plpgsql STABLE SECURITY DEFINER
SET search_path = app, public
AS $$ DECLARE v_result TYPE; BEGIN
    -- Logic
    RETURN v_result;
EXCEPTION WHEN OTHERS THEN
    RAISE WARNING '%', SQLERRM;
    RETURN NULL;
END; $$;

Trigger Template

CopyCREATE OR REPLACE FUNCTION trigger_func() RETURNS TRIGGER AS $$
BEGIN
    IF TG_OP = 'UPDATE' THEN NEW.updated_at := NOW(); END IF;
    RETURN NEW;
END; $$ LANGUAGE plpgsql;

CREATE TRIGGER trg_name BEFORE UPDATE ON t FOR EACH ROW EXECUTE FUNCTION trigger_func();

Volatility

Exception Handling

CopyEXCEPTION
    WHEN unique_violation THEN ...  -- 23505
    WHEN foreign_key_violation THEN ...  -- 23503
    WHEN OTHERS THEN RAISE EXCEPTION '% [%]', SQLERRM, SQLSTATE;

Troubleshooting

Usage

CopySkill("postgresql-plpgsql")