---
name: db-schema-change
description: Handle Drizzle database schema changes safely. Generate and apply migrations, add tables and columns. Use when modifying database schema, adding tables, creating migrations, or making database changes.
allowed-tools: Read, Grep, Glob, Write, Edit, Bash
---

# Database Schema Change

Safely modify PostgreSQL schema using Drizzle ORM.

## When to Use

- "Add a new table for..."
- "Add column to..."
- "Create migration for..."
- "Modify database schema"
- "Add foreign key to..."

## Important Files

| File                             | Purpose               |
| -------------------------------- | --------------------- |
| `packages/db/src/schema.ts`      | Main schema exports   |
| `packages/db/src/auth-schema.ts` | Better Auth tables    |
| `packages/db/src/rag-schema.ts`  | RAG embeddings tables |
| `packages/db/drizzle/`           | Generated migrations  |

## Procedure

### Step 1: Understand Current Schema

Read the schema file to understand existing tables:

```
Read: packages/db/src/schema.ts
```

### Step 2: Plan the Change

Before making changes, confirm with user:

- Table name and column definitions
- Data types (see [types.md](./types.md))
- Relationships (foreign keys)
- Indexes needed
- Whether data migration is required

### Step 3: Modify Schema

Edit the appropriate schema file:

```typescript
// packages/db/src/schema.ts
import { pgTable, text, timestamp, uuid } from 'drizzle-orm/pg-core';

export const newTable = pgTable('new_table', {
  id: uuid('id').primaryKey().defaultRandom(),
  name: text('name').notNull(),
  createdAt: timestamp('created_at').defaultNow().notNull(),
  updatedAt: timestamp('updated_at').defaultNow().notNull(),
});
```

### Step 4: Generate Migration

Run migration generator:

```bash
pnpm -C packages/db migrate:generate
```

### Step 5: Review Migration

Read the generated migration in `packages/db/drizzle/` and verify:

- Correct SQL statements
- No data loss for existing tables
- Proper indexes created

### Step 6: Apply Migration (Local)

```bash
pnpm -C packages/db migrate:apply
```

### Step 7: Verify

```bash
pnpm typecheck
pnpm lint
```

## Checklist

- [ ] Schema change planned with user
- [ ] Schema file updated
- [ ] Migration generated
- [ ] Migration reviewed (no data loss)
- [ ] Migration applied locally
- [ ] TypeScript compiles
- [ ] Existing tests still pass

## Guardrails

- NEVER drop columns without explicit user confirmation
- NEVER run migrations on production directly (CI handles this)
- ALWAYS generate migration before applying
- ALWAYS review generated SQL before applying
- If migration involves data transformation, create separate script
- Ask user before destructive changes (DROP, TRUNCATE)


---
Source attribution: jamesjlundin
Original project: https://github.com/jamesjlundin/full-stack-web-and-mobile-template/blob/99f167760872f225b8adc0495237a7e636a99c31/.claude/skills/db-schema-change/SKILL.md
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Dave AI.

## Upstream license notice

MIT License

Copyright (c) 2025 James Lundin

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Dave AI resource metadata

Creator / publisher: jamesjlundin
Original project: https://github.com/jamesjlundin/full-stack-web-and-mobile-template/blob/99f167760872f225b8adc0495237a7e636a99c31/.claude/skills/db-schema-change/SKILL.md
Attribution basis: Recovered original package and original project license at a pinned revision

Fields of work: Development & Engineering
Roles: Backend Developer, Data Engineer, Database Administrator
Specialties: Database
Tools: PostgreSQL
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 1252c7b1edb25526d36fb9553235f18318c24dc0442be4ac004fc17464b61fa5
Metadata reviewed: 2026-10-27
This metadata supersedes earlier Dave AI catalog attribution. Original instruction and supporting files are preserved.