Instead of applying schema changes from the release pipeline, they can also be applied by the application itself. Some of the ORMs, with migration support built in, have the capability to automatically detect whether the database schema matches the latest migration. If not, they can automatically migrate the schema to that latest version on the spot.

An example of an ORM that supports this is Entity Framework. The core version of Entity Framework does not have support for automatic migrations built in. In Entity Framework Core, a single line of application code can be used to initiate an upgrade at a time that is convenient from the perspective of the application. The code for doing so is shown in the following code snippet:

using (var context = new MyContext(...))
{
    context.Database.Migrate();
}

The advantage of this approach is that it is very simple to enable. Just a Boolean switch in the configuration of, for example, Entity Framework can enable this workflow. However, the disadvantage is that most ORMs that support this will enforce a global lock on the database—stopping all database transactions while the migrations are running. For any migration or set of migrations that take more than a few seconds, this approach might be impractical.

This approach is normally only used for migration-based approaches. Approaches that use an end-state approach require an external third-party tool that is used to generate the necessary migration scripts and apply them. This is normally done from the release pipeline and is not wrapped in the application itself.