TypeORM Migrations

Create and manage database schema changes with TypeORM migrations.

Overview

Migrations track schema changes in a version-controlled way, allowing safe database evolution.

Creating a Migration

Auto-Generate from Entity Changes

yarn typeorm migration:generate -n AddEmployeePhoneColumn

This compares current entities against the database and generates SQL.

Manual Migration

yarn typeorm migration:create -n CustomMigration

Migration File Structure

import { MigrationInterface, QueryRunner } from "typeorm";

export class AddEmployeePhoneColumn1709635260000 implements MigrationInterface {
  name = "AddEmployeePhoneColumn1709635260000";

  public async up(queryRunner: QueryRunner): Promise<void> {
    await queryRunner.query(`
      ALTER TABLE "employee"
      ADD COLUMN "phoneNumber" varchar(20)
    `);
  }

  public async down(queryRunner: QueryRunner): Promise<void> {
    await queryRunner.query(`
      ALTER TABLE "employee"
      DROP COLUMN "phoneNumber"
    `);
  }
}

Running Migrations

# Run pending migrations
yarn typeorm migration:run

# Revert last migration
yarn typeorm migration:revert

# Show migration status
yarn typeorm migration:show

Best Practices

Practice	Description
Always write down()	Enable rollback
Test on staging first	Verify before production
Backup before migration	Safety net
Use transactions	Atomic changes
No data loss	Add columns as nullable first
Sequential naming	Timestamps in filenames

Migration Directory

packages/core/src/database/migrations/
├── 1700000000001-InitialSchema.ts
├── 1700000000002-AddTimeTracking.ts
└── 1700000000003-AddCRMTables.ts

Related Pages

• Database Schema — schema overview
• MikroORM Migrations — MikroORM alternative
• SQLite to PostgreSQL — DB migration