MERGE INTO 两个表实现数据同步

语法：

MERGE INTO 表A USING 表B

ON 关联条件

WHEN MATCHED THEN 满足执行

WHEN NOT MATCHED THEN 不满足执行

merge into [dbo].[T_Class_B]
using [dbo].[T_Class_A] -- 这里的[dbo].[T_Class_A]也可以是子查询
on [T_Class_A].[ClassName]=[T_Class_B].[ClassName]
when matched 
then update  set [T_Class_B].[StudentTotalCount]=[T_Class_A].[StudentTotalCount],[T_Class_B].[Owner]=[T_Class_A].[Owner]
when not matched
then insert([ClassName],[StudentTotalCount],[Owner]) values([T_Class_A].[ClassName],[T_Class_A].[StudentTotalCount],[T_Class_A].[Owner]);