Orphan User:

An orphan user is a user in a SQL Server database that is not associated with a SQL Server login.


-- Script to check the orphan user
EXEC sp_change_users_login 'Report'
--Use below code to fix the Orphan User issue
DECLARE @username varchar(25)
DECLARE fixOrphanusers CURSOR
FOR
SELECT UserName = name FROM sysusers
WHERE issqluser = 1 and (sid is not null and sid <> 0x0)
and suser_sname(sid) is null
ORDER BY name
OPEN fixOrphanusers
FETCH NEXT FROM fixOrphanusers
INTO @username
WHILE @@FETCH_STATUS = 0
BEGIN
EXEC sp_change_users_login 'update_one', @username, @username
FETCH NEXT FROM fixOrphanusers
INTO @username
END
CLOSE fixOrphanusers
DEALLOCATE fixOrphanusers