--WHEN  NOT MATCHED  BY Source 和WHEN  NOT MATCHED  BY TARGET 是固定格式
--用USING中查到的数据S 对T表来操作
 MERGE INTO [Admin] T  
                USING Admin2 AS S  
                ON ( T.LoginId = S.LoId ) 
                WHEN  NOT MATCHED  BY TARGET THEN  --目标表(T)中不存在  源表(S)中存在  
                INSERT (LoginId ,LoginPwd )
                VALUES (s.loid ,s.lopwd);
go
 MERGE INTO [Admin] T  
                USING Admin2 AS S
                ON ( T.LoginId = S.LoId ) 
                WHEN  NOT MATCHED  THEN  --目标表(T)中不存在  源表(S)中存在   
                INSERT (LoginId ,LoginPwd )
                VALUES (s.loid ,s.lopwd);
go
 MERGE INTO [Admin] T   
                USING Admin2 AS S
                ON ( T.LoginId = S.LoId ) 
                WHEN  NOT MATCHED  BY Source THEN  --目标表(T)中存在  源表(S)中不存在
                delete;
go

 WHEN MATCHED 是当上面条件成立 执行下面操作

WHEN MATCHED 后面可以跟 and

WHEN  NOT MATCHED  BY Source 和 WHEN  NOT MATCHED  BY TARGET 是固定格式

WHEN  NOT MATCHED  BY TARGET 和  WHEN  NOT MATCHED 相同

用Using中查到的数据S 对 T操作