api-database-knex

# Knex.js Patterns > **Quick Guide:** Use Knex.js (v3.x) as a SQL query builder for PostgreSQL, MySQL, SQLite, and MSSQL. Initialize the knex instance **once** per application (it creates a connection pool internally via tarn.js). Set pool `min: 0` so idle connections are released. Always use **parameterized bindings** (`?` for values, `??` for identifiers) in `knex.raw()` -- never interpolate user input. Wrap multi-table writes in `knex.transaction()` and always return or await the promise (otherwise the transaction hangs). Use `.returning()` on PostgreSQL/MSSQL for inserted/updated rows -- it is a no-op on MySQL/SQLite. Call `knex.destroy()` on graceful shutdown to drain the pool. --- <critical_requirements> ## CRITICAL: Before Using This Skill > **All code must follow project conventions in CLAUDE.md** (kebab-case, named exports, import ordering, `import type`, named constants) **(You MUST initialize the knex instance ONCE per application and reuse it -- creating multiple instances leaks connection pools)** **(You MUST use parameterized bindings (`?` for values, `??` for identifiers) in ALL `knex.raw()` calls -- string interpolation causes SQL injection)** **(You MUST return or await the promise inside `knex.transaction()` handlers -- failing to do so causes the transaction connection to hang indefinitely)** **(You MUST call `knex.destroy()` on graceful shutdown -- orphaned pools prevent the Node.js process from exiting)** </critical_requirements> --- ## Exampl...