Solve the problem of "User, group, or role already exists in the current database" in the SQL Server database.

Problem scenarios

During SQL Server database migration, after recovering the database backup file on another Server, you need to recreate the user account on the database. When creating a login User, you must authorize the User in User Mapping for the specific database. Because the recovered database contains a User account with the same name, "User, group, or role already exists in the current database "error message. The error details are as follows:

TITLE: Microsoft SQL Server Management Studio
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Create failed for User 'testuser'. (Microsoft. SqlServer. Smo)
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Additional information:
An exception occurred while executing a Transact-SQL statement or batch. (Microsoft. SqlServer. ConnectionInfo)
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User, group, or role 'testuser' already exists in the current database. (Microsoft SQL Server, Error: 15023)

Previous solutions

Before creating a user account (or authorization), delete the user account with the same name in the corresponding database.

Latest Solution

Create a user account without authorization, and then associate the account with the corresponding database user using the following SQL statement. This avoids re-authorization.

USE {target database} EXEC sp_change_users_login 'Update _ one', '{existing username of the target database}', '{created username }'

Method Source

SQL Server Forums-How to assign a login to an existing user?