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Migrations

The .sq file always describes how to create the latest schema in an empty database. If your database is currently on an earlier version, migration files bring those databases up-to-date.

Versioning

The first version of the schema is 1. Migration files are named <version to upgrade from>.sqm. To migrate to version 2, put migration statements in 1.sqm:

ALTER TABLE hockeyPlayer ADD COLUMN draft_year INTEGER;
ALTER TABLE hockeyPlayer ADD COLUMN draft_order INTEGER;

These SQL statements are run by Database.Schema.migrate().

Verifying Migrations

You can also place a .db file in the src/main/sqldelight folder of the same <version number>.db format. If there is a .db file present, a new verifySqlDelightMigration task will be added to the gradle project, and it will run as part of the test task, meaning your migrations will be verified against that .db file. It confirms that the migrations yield a database with the latest schema.

To generate a .db file from your latest schema, run the generateSqlDelightSchema task, which is available once you specify a schemaOutputDirectory, as described in the gradle.md. You should probably do this before you create your first migration.