[SQL] 使用者群組或角色在XXX的目前資料庫中已經存在

解
exec sp_change_users_login 'Update_One','XXX','XXX'

詳解sp_change_users_login參數
https://docs.microsoft.com/zh-tw/sql/relational-databases/system-stored-procedures/sp-change-users-login-transact-sql?view=sql-server-2017

查詢被遺棄的使用者
SELECT dp.type_desc, dp.SID, dp.name AS user_name 
FROM sys.database_principals AS dp 
LEFT JOIN sys.server_principals AS sp 
    ON dp.SID = sp.SID 
WHERE sp.SID IS NULL 
    AND authentication_type_desc = 'INSTANCE';