# Database Migrations

> Manage database schema changes using migration tools and version control.

- Skill: `heldinhow/database-migrations` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add heldinhow/database-migrations`
- Raw SKILL.md: https://api.skillmd.com/api/skills/heldinhow/database-migrations/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: Heldinhow (https://skillmd.com/u/heldinhow)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/heldinhow/database-migrations

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# Database Migrations

## Overview
Database migrations manage schema changes in a controlled, versioned manner, enabling safe evolution of database structure. This skill should be invoked when evolving database schema, managing team database development, or rolling back problematic changes.

## Core Principles
- **Version Control**: Store migrations in version control alongside code
- **Idempotency**: Migrations should be safe to run multiple times
- **Forward and Backward**: Support both applying and rolling back changes
- **Small Batches**: Prefer small, focused migrations over large ones

## Preparation Checklist
- [ ] Choose migration tool (Alembic, Prisma, TypeORM, Flyway)
- [ ] Initialize migration system in project
- [ ] Set up migration tracking table
- [ ] Define naming convention for migrations

## Step-by-Step Process
1. **Initialize**: Set up migration system for your ORM/tool
2. **Create**: Generate migration file for schema changes
3. **Review**: Verify migration SQL before applying
4. **Run**: Execute migrations in correct order
5. **Rollback**: Test rollback procedures
6. **Verify**: Confirm migration success

## Do's and Don'ts
- ✅ **Do** test migrations in staging before production
- ✅ **Do** back up production database before running migrations
- ✅ **Do** keep migrations small and focused
- ❌ **Don't** edit applied migrations - create new ones
- ❌ **Don't** skip testing rollbacks
- ❌ **Don't** run manual SQL outside of migrations

## Anti-Patterns
- **Manual Changes**: Making schema changes directly in production
- **Lost Migrations**: Not version-controlling migration files
- **No Rollback**: Not planning for reversibility
- **Large Migrations**: Trying to do too much in one migration