Why are two migrations usually created for one change in the database?

Two migrations for a single database change are usually created for safe and phased implementation of changes, especially if they involve the structure of tables with large amounts of data or critical relationships.

The first migration makes changes that do not break the current code (for example, adding new columns or tables). After the code is updated and starts using the new structure, the second migration removes outdated elements (for example, old columns or tables).

This approach helps avoid downtime and errors related to schema and code incompatibility during deployment.