Fix Orphaned Users When Moving SQL Server Databases
Firstly to report on whether there are any orphaned users present for a database, run the following query against the DB;
EXEC sp_change_users_login 'Report'
Then to fix any identified orphaned queries, you can either attempt to fix this automatically via:
EXEC sp_change_users_login 'Auto_Fix', 'user'
… or manually (with more control) via the following query:
sp_change_users_login 'update_one', 'dbUser', 'sqlLogin'
Alternatively
EXEC sp_change_users_login 'Auto_Fix', 'user', 'login', 'password'