How to use a different connection string (but same database) for migrations

Question

I have been using a connection string like this to connect my website to my database:

Answer 1

I finally solved this by adding the website_staging_migrations user to the db_datareader and db_datawriter roles as well as the db_ddladmin role.

The user obviously needs to read the data in the __MigrationHistory table. What threw me was that EF doesn't report the failure to access the table as an error and instead I got this error when it tried to run the initial migration:

There is already an object named '----' in the database.

And the user also needs to write to the __MigrationHistory table. I got this error until I added the user to the db_datawriter role:

The INSERT permission was denied on the object '__MigrationHistory',
database 'Staging', schema 'dbo'.