Apply previously generated SQL migration files to a database, either via the `drizzle-kit migrate` CLI command or programmatically at runtime with drizzle-orm's `migrate()` function.

Documented steps

1. Ensure `dbCredentials` is set in `drizzle.config.ts` alongside `dialect`, e.g.: `dbCredentials: { url: "postgresql://user:password@host:port/dbname" }` (for Postgres, connection-param form is also supported: `host`, `port`, `user`, `password`, `database`, `ssl`).
2. Run `npx drizzle-kit migrate` (optionally `--config=drizzle-prod.config.ts` for a specific environment). It reads `.sql` files in the `out` folder, fetches applied-migration history from the database, and applies any unapplied ones in order.
3. Applied migrations are logged in a table, default name `__drizzle_migrations` in schema `drizzle`. Customize via config: `migrations: { table: 'my-migrations-table', schema: 'my_schema' }`.
4. For runtime/programmatic application (e.g. serverless cold start, zero-downtime deploy) instead of the CLI, import the driver-specific migrator and call it, exactly as documented: `import { drizzle } from "drizzle-orm/node-postgres"; import { migrate } from 'drizzle-orm/node-postgres/migrator'; const db = drizzle(process.env.DATABASE_URL); await migrate(db);`
5. This runtime approach is commonly used for monolithic apps applying migrations during zero-downtime deploys, or serverless deployments running migrations once via a custom deploy resource.
6. Reference: https://orm.drizzle.team/docs/drizzle-kit-migrate https://orm.drizzle.team/docs/migrations https://orm.drizzle.team/docs/drizzle-config-file