Business logic encapsulation
Complex multi-step operations
Data validation and constraints
Audit trail maintenance
Performance optimization
Code reusability across applications
Trigger-based automation

Quick Start

PostgreSQL - Scalar Function:

-- Create function returning single value
CREATE OR REPLACE FUNCTION calculate_order_total(
  p_subtotal DECIMAL,
  p_tax_rate DECIMAL,
  p_shipping DECIMAL
)
RETURNS DECIMAL AS $$
BEGIN
  RETURN ROUND((p_subtotal * (1 + p_tax_rate) + p_shipping)::NUMERIC, 2);
END;
$$ LANGUAGE plpgsql IMMUTABLE;

-- Use in queries
SELECT id, subtotal, calculate_order_total(subtotal, 0.08, 10) as total
FROM orders;

-- Or in application code
SELECT * FROM orders
WHERE calculate_order_total(subtotal, 0.08, 10) > 100;

Reference Guides

Detailed implementations in the references/ directory:

Guide	Contents
Simple Functions	Simple Functions
Stored Procedures	Stored Procedures
Simple Procedures	Simple Procedures
Complex Procedures with Error Handling	Complex Procedures with Error Handling
PostgreSQL Triggers	PostgreSQL Triggers
MySQL Triggers	MySQL Triggers

Best Practices

✅ DO

Follow established patterns and conventions
Write clean, maintainable code
Add appropriate documentation
Test thoroughly before deploying

❌ DON'T

Skip testing or validation
Ignore error handling
Hard-code configuration values

stored-procedures

Stored Procedures & Functions

Table of Contents

Overview

When to Use