---
title: Use Database Migrations
impact: HIGH
impactDescription: Enables safe, repeatable database schema changes
tags: database, migrations, drizzle, schema
---

## Use Database Migrations

Never push schema changes with `drizzle-kit push` in production. Use versioned SQL migrations for all schema changes. Migrations provide version control for your database, enable safe rollbacks, and ensure consistency across all environments.

**Incorrect (pushing schema or running ad-hoc SQL):**

```typescript
// drizzle-kit push against production
// Mutates the live database with no rollback file

@Injectable()
export class DatabaseService {
  async addColumn(): Promise<void> {
    await this.db.execute(sql`ALTER TABLE users ADD COLUMN age INT`);
  }
}
```

**Correct (generate and apply Drizzle migrations):**

```typescript
// drizzle.config.ts
import { defineConfig } from 'drizzle-kit';

export default defineConfig({
  schema: './drizzle/schema.ts',
  out: './drizzle/migrations',
  dialect: 'postgresql',
  dbCredentials: {
    url: process.env.DATABASE_URL!,
  },
});
```

```bash
# Generate a migration from schema diffs
npx drizzle-kit generate

# Apply migrations
npx drizzle-kit migrate
```

```typescript
// drizzle/schema.ts
export const users = pgTable('users', {
  id: uuid('id').primaryKey().defaultRandom(),
  email: varchar('email', { length: 255 }).notNull(),
  age: integer('age').default(0),
});
```

Always keep `down`/rollback SQL when a migration is destructive. Never edit an already-applied migration file; add a new one.

Reference: [Drizzle Kit Migrations](https://orm.drizzle.team/docs/kit-overview)