优化M有School 第四章课后3 借阅事务

BEGIN TRANSACTIONDECLARE @errorSum intDECLARE @RID varchar(50)DECLARE @BID varchar(50)SELECT @RID=RID FROM Reader WHERE RName='张无忌'SELECT @BID=BID FROM Book WHERE BName='深入。Net平台和c#编程'SET @errorSum=0INSERT INTO Borrow(RID,BID)VALUES (@RID,@BID)SET @errorSum=@errorSum+@@errorUPDATE Book SET BCount=BCount-1 WHERE BName=' 深入。Net平台和c#编程'SET @errorSum=@errorSum+@@errorUPDATE Reader SET LendNum=LendNum+1 WHERE RName='张无忌'SET @errorSum=@errorSum+@@errorIF @errorSum<>0ROLLBACK TRANSACTIONELSE COMMIT TRANSACTIONGO