A migration script changes all or part of a database from one version to another. It migrates it between version. This alteration can be done by simply adding or removing a column to a table, or a complex refactoring task like splitting tables or changing column properties.
For every migration path between database version, we need to store in version control the migration scripts that describe those steps required to transform, change, and move the data and moving it around and transforming it in the process.
Migration scripts can be forward, or up migration that go to a newer version of the database, or backwards or down to fall back to the previous version of a database.
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