Drizzle ORM TypeSafe Database Access

Lightweight, headless TypeScript ORM with zero dependencies. Drizzle excels at:

Type inference — Full TypeScript types from schema; no generated types or separate schema language
Relational queries — Fetch nested data with .with() without manual joins
Prepared statements — Pre-compile queries for repeated execution; significant performance boost
Migrations — Version-controlled schema changes with drizzle-kit; rollback support
Transactions — Atomic multi-operation commits with savepoints for nested transactions

Core patterns: one table per file, relational API for nested queries, prepared statements for hot paths, transactions for consistency.

Workflow

When working with Drizzle ORM:

Design schema — Tables, columns, constraints; one file per table
Define relations — defineRelations() for one-to-many, many-to-many; enables nested queries
Choose query style — Relational API for nested data (prefer), SQL builder for flexibility
Optimize hot paths — Use prepared statements with placeholders for repeated queries
Handle transactions — Wrap multi-operation writes in db.transaction()
Test migrations — drizzle-kit migrate:dev before push; review generated SQL
Type extraction — Use InferSelectModel for runtime types from schema

Patterns are organized by concern:

Schema — Table design, column types, constraints, one file per table
Relational Queries — with() for nested data, partial columns, filtering
Query Builder — SQL builder for aggregations and complex queries
Prepared Statements — Pre-compile for performance; use placeholders for parameters
Migrations — Version control, review SQL, push vs generate
Transactions — Atomic operations, savepoints, error handling

See rules/ for implementation patterns and examples.

User: "Define a Drizzle schema for orders with relations to users and products."

Expected behavior: Use tech-drizzle guidance, apply schema design with relational queries and type inference.

User: "Write a raw SQL migration for adding a column to the users table."

Expected behavior: Do not prioritize tech-drizzle; choose a more relevant skill or proceed without it.

Error: Running unprepared queries in tight loops
Cause: Query compiled every execution; no reuse of parsed SQL
Solution: Use .prepare() with placeholders; execute multiple times with different params
Error: Manual joins in code; fetching parent then children separately
Cause: Not using relational API; writing complex join logic
Solution: Define relations, use .with() to fetch nested data in single query

Error: Column not included in result when selecting from relation
Cause: Selecting from nested relation without explicitly including columns
Solution: Use columns: { id: true, name: true } to specify nested relation columns
Error: Transaction rolls back unexpectedly; no clear error
Cause: Unhandled promise rejection inside db.transaction()
Solution: Wrap transaction operations in try/catch; all errors must be caught
Error: Schema types not updating after migration
Cause: drizzle-kit didn't regenerate types; cache stale
Solution: Run drizzle-kit generate after migration changes