SKILL.md
Database Schema Design
Table of Contents
- [Overview](#overview)
- [When to Use](#when-to-use)
- [Quick Start](#quick-start)
- [Reference Guides](#reference-guides)
- [Best Practices](#best-practices)
Overview
Design scalable, normalized database schemas with proper relationships, constraints, and data types. Includes normalization techniques, relationship patterns, and constraint strategies.
When to Use
- New database schema design
- Data model planning
- Table structure definition
- Relationship design (1:1, 1:N, N:N)
- Normalization analysis
- Constraint and trigger planning
- Performance optimization at schema level
Quick Start
PostgreSQL - Eliminate Repeating Groups:
-- NOT 1NF: repeating group in single column
CREATE TABLE orders_bad (
id UUID PRIMARY KEY,
customer_name VARCHAR(255),
product_ids VARCHAR(255) -- "1,2,3" - repeating group
);
-- 1NF: separate table for repeating data
CREATE TABLE orders (
id UUID PRIMARY KEY,
customer_name VARCHAR(255),
created_at TIMESTAMP DEFAULT NOW()
);
CREATE TABLE order_items (
id UUID PRIMARY KEY,
order_id UUID NOT NULL,
product_id UUID NOT NULL,
quantity INTEGER NOT NULL,
FOREIGN KEY (order_id) REFERENCES orders(id) ON DELETE CASCADE
);Reference Guides
Detailed implementations in the references/ directory:
| Guide | Contents |
|---|---|
| First Normal Form (1NF) | First Normal Form (1NF) |
| Second Normal Form (2NF) | Second Normal Form (2NF) |
| Third Normal Form (3NF) | Third Normal Form (3NF) |
| Entity-Relationship Patterns | Entity-Relationship Patterns |
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