Database Migration

2. Generate Migration

Run the migration generation command:

<generate-command>

This command:

• Analyzes your schema changes
• Creates a new migration file in <migrations-dir>
• Names it with a timestamp and description

Example output:

✔ Loaded env from .env
✔ Pulling schema from database...
✔ Pulling migration state...
✔ Loaded all config
✔ Pulling existing migrations...
◐ Pulling schema from database...0001_new_field_migration.sql migrated!

3. Review the Migration

Check the generated migration file in <migrations-dir>:

-- Example: migrations/0001_add_new_field.sql
ALTER TABLE "users" ADD COLUMN "new_field" text;

Important: Review the SQL to ensure it matches your intentions.

4. Apply the Migration

Run the migration to update your database:

<migrate-command>

This applies all pending migrations to your database.

5. Verify Changes

Open Drizzle Studio to verify:

<studio-command>

Check:

• New columns appear
• Data is preserved
• Constraints are applied

6. Commit Changes

Always commit both files together:

git add <schema-file> <migrations-dir>/
git commit -m "feat: add new_field to users table"

Common Scenarios

Adding a New Table

export const newTable = pgTable("new_table", {
  id: text("id").primaryKey().$defaultFn(() => crypto.randomUUID()),
  name: text("name").notNull(),
  createdAt: timestamp("created_at").defaultNow().notNull(),
});

Adding a Foreign Key

export const posts = pgTable("posts", {
  id: text("id").primaryKey(),
  userId: text("user_id")
    .notNull()
    .references(() => users.id, { onDelete: "cascade" }),
  // other fields...
});

Making a Field Required

// Before