这两中事务写法有什么不同
BEGIN TRAN T1
UPDATE table1 ...
BEGIN TRAN M2 WITH MARK
UPDATE table2 ...
SELECT * from table1
COMMIT TRAN M2
UPDATE table3 ...
COMMIT TRAN T1
与
BEGIN TRAN T1
UPDATE table1 ...
--BEGIN TRAN M2 WITH MARK
UPDATE table2 ...
SELECT * from table1
--COMMIT TRAN M2
UPDATE table3 ...
COMMIT TRAN T1
有什么不同吗