[英]Correct use of transactions in SQL Server
I have 2 commands and need both of them executed correctly or none of them executed. 我有2个命令,需要它们都正确执行或者没有执行。 So I think I need a transaction, but I don't know how to use it correctly.
所以我认为我需要一个交易,但我不知道如何正确使用它。
What's the problem with the following script? 以下脚本有什么问题?
BEGIN TRANSACTION [Tran1]
INSERT INTO [Test].[dbo].[T1]
([Title], [AVG])
VALUES ('Tidd130', 130), ('Tidd230', 230)
UPDATE [Test].[dbo].[T1]
SET [Title] = N'az2' ,[AVG] = 1
WHERE [dbo].[T1].[Title] = N'az'
COMMIT TRANSACTION [Tran1]
GO
The INSERT
command is executed, but the UPDATE
command has a problem. 执行
INSERT
命令,但UPDATE
命令有问题。
How can I implement this to rollback both commands if any of them have an error in execution? 如果其中任何一个命令执行错误,我如何实现它来回滚这两个命令?
Add a try/catch block, if the transaction succeeds it will commit the changes, if the transaction fails the transaction is rolled back: 添加一个try / catch块,如果事务成功,它将提交更改,如果事务失败,则事务将被回滚:
BEGIN TRANSACTION [Tran1]
BEGIN TRY
INSERT INTO [Test].[dbo].[T1] ([Title], [AVG])
VALUES ('Tidd130', 130), ('Tidd230', 230)
UPDATE [Test].[dbo].[T1]
SET [Title] = N'az2' ,[AVG] = 1
WHERE [dbo].[T1].[Title] = N'az'
COMMIT TRANSACTION [Tran1]
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION [Tran1]
END CATCH
At the beginning of stored procedure one should put SET XACT_ABORT ON to instruct Sql Server to automatically rollback transaction in case of error. 在存储过程开始时,应该将SET XACT_ABORT设置为ON,以指示Sql Server在发生错误时自动回滚事务。 If ommited or set to OFF one needs to test @@ERROR after each statement or use TRY ... CATCH rollback block.
如果ommited或设置为OFF,则需要在每个语句后测试@@ ERROR或使用TRY ... CATCH回滚块。
Easy approach: 简单方法:
CREATE TABLE T
(
C [nvarchar](100) NOT NULL UNIQUE,
);
SET XACT_ABORT ON -- Turns on rollback if T-SQL statement raises a run-time error.
SELECT * FROM T; -- Check before.
BEGIN TRAN
INSERT INTO T VALUES ('A');
INSERT INTO T VALUES ('B');
INSERT INTO T VALUES ('B');
INSERT INTO T VALUES ('C');
COMMIT TRAN
SELECT * FROM T; -- Check after.
DELETE T;
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