How to Provide Database Schema Context in Cursor

Direct Answer: To give Cursor database context without blowing up your context window or manually pasting DDL, create a scoped rule at .cursor/rules/database.mdc configured with file globs (e.g. ["**/*.sql", "src/backend/**"]) and alwaysApply: false. Rather than dumping raw SQL tables, compile a compressed relationship graph with explicit [SAFETY] guardrails using schemap agents --targets cursor.

1. The Global "Context Window Tax"

Putting 500 lines of raw SQL into a global .cursorrules file injects 15,000+ tokens into every single chat and Composer prompt—even when you are simply tweaking CSS or writing React frontend components. This slows down generation latency and dramatically increases API costs.

2. Lack of Explicit JOIN Topologies

Raw CREATE TABLE statements list column names alphabetically or sequentially. LLMs struggle to deduce multi-hop relational paths across junction tables (e.g., finding the shortest path from invoices to customer_profiles via accounts).

3. Frequent Schema Drift & Stale Context

Whenever a team member runs an ORM migration (Prisma, Drizzle, Alembic), static markdown files quickly become stale unless they are compiled into git pre-commit hooks.

Step 1: Install Schemap CLI

Install Schemap globally on your development machine in 5 seconds:

$ pipx install schemap-tool
# or with uv:
$ uv tool install schemap-tool

Step 2: Generate `.cursor/rules/database.mdc`

Run the native agent rule generator pointing to your database connection string:

$ export DATABASE_URL="postgresql://user:pass@localhost:5432/mydb"
$ schemap agents --targets cursor

In less than 3 milliseconds, Schemap inspects your database catalogs and generates a perfectly formatted .cursor/rules/database.mdc:

---
description: Database schema context and anti-hallucination rules
globs: ["**/*.sql", "src/services/**", "app/api/**", "src/models/**"]
alwaysApply: false
---

# Database Context (Compiled by Schemap)
## Summary: 12 Tables | Key Entities: users, orders, subscriptions

### Relationships & Join Map:
- orders.user_id -> users.id
- order_items.order_id -> orders.id
- order_items.product_id -> products.id
- subscriptions.account_id -> accounts.id

### [SAFETY] Anti-Hallucination Guardrails:
- NEVER join `orders` to `users` on `customer_id`.
- DO NOT SELECT `users.password_hash` in API responses.

Step 3: Enable Automated Pre-Commit Sync

Ensure Cursor always has up-to-date schema context whenever migrations are modified:

$ schemap hook install

This registers a lightweight pre-commit hook that re-compiles .cursor/rules/database.mdc whenever database migration files or schemas are modified.

Step 4: Use `@` Mentions in Cursor Chat & Composer

When working on complex backend tasks, you can explicitly summon your database rule by typing @database.mdc in Cursor Chat or Composer, or rely on Cursor's glob matching when editing SQL and backend files.