# Database Migrations

The folder for all migration files.

## Format

The migration files are named in the format of `<version>.ts` where `version` is this npm package's version number.

As for development, the `version` is "next" until the package is released.

## Typing

```ts
type MigrationScript = {
  up: (connection: DatabaseTransactionConnection) => Promise<void>;
  down: (connection: DatabaseTransactionConnection) => Promise<void>;
};
```

When the migration script is executed, the `up` function is called to alter the database schema.

The `down` function is designed for the future downgrade feature.

## Example

```ts
export const up = async (connection) => {
  await connection.query(`
    ALTER TABLE "user"
    ADD COLUMN "email" VARCHAR(255) NOT NULL;
  `);
};

export const down = async (connection) => {
  await connection.query(`
    ALTER TABLE "user"
    DROP COLUMN "email";
  `);
};
```