SQL Server:错误处理及事务控制
目录：
解读错误信息
RAISERROR
THROW
实例
使用 @@ERROR
使用 XACT_ABORT
使用TRY/CATCH
现实中的事务语句
删除
更新
银行取钱
解读错误信息
Msg 547, Level 16, State 0, Line 11 The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Products_Categories". The conflict occurred in database "TSQL2012", table "Production.Categories", column 'categoryid'.
Error number
● SQL Server 错误信息的编号从1~49999
● 自定义错误信息从50001开始
● 错误编号50000是为没有错误编号的自定义信息准备的。
Severity level
SQL Server 一共26个严重级别 0~25。
● 严重级别>= 16的会记录SQL Server日志和Windows 应用程序日志
● 严重级别19~25 只能由 sysadmin觉得的成员处理
● 严重级别20~25被认为是致命错误。 会中断终端连接并回滚所有打开的事务。
● 严重级别0~10只是提示信息。
State int 类型，最大值127， MS internal purposes
Error message 支持255个Unicode 字符
● SQL Server 错误信息都在 sys.messages里面
● 可以用sp_addmessage 添加自定义错误信息
RAISERROR（不会中断事务）
简单的传递信息可以使用级别0~9 。
如果你有sysadmin的角色，可以使用WITH LOG选项并设置一个严重级别>20的错误。error 发生的时候SQL Server会中断连接。
使用NOWAIT选项可以直接发送信息，而不用等大赛buffer
RAISERROR ('Error in usp_InsertCategories stored procedure', 16, 0);
-- Formatting the RAISERROR string
RAISERROR ('Error in % stored procedure', 16, 0, N'usp_InsertCategories');
-- In addition, you can use a variable:
GO
DECLARE @message AS NVARCHAR(1000) = N'Error in % stored procedure';
RAISERROR (@message, 16, 0, N'usp_InsertCategories');
-- And you can add the formatting outside RAISERROR using the FORMATMESSAGE function:
GO
DECLARE @message AS NVARCHAR(1000) = N'Error in % stored procedure';
SELECT @message = FORMATMESSAGE (@message, N'usp_InsertCategories');
RAISERROR (@message, 16, 0);
THROW （会中断事务）
-- You can issue a simple THROW as follows: THROW 50000, 'Error in usp_InsertCategories stored procedure', 0; -- Because THROW does not allow formatting of the message parameter, you can use FORMATMESSAGE() GO DECLARE @message AS NVARCHAR(1000) = N'Error in % stored procedure'; SELECT @message = FORMATMESSAGE (@message, N'usp_InsertCategories'); THROW 50000, @message, 0;
-- RAISERROR does not normally terminate a batch:
RAISERROR ('Hi there', 16, 0);
PRINT 'RAISERROR error'; -- Prints
GO
-- However, THROW does terminate the batch:
THROW 50000, 'Hi there', 0;
PRINT 'THROW error'; -- Does not print
GO
实例
使用 @@ERROR
DECLARE @errnum AS int;
BEGIN TRAN;
SET IDENTITY_INSERT Production.Products ON;
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(1, N'Test1: Ok categoryid', 1, 1, 18.00, 0);
SET @errnum = @@ERROR;
IF @errnum <> 0 -- Handle the error
BEGIN
PRINT 'Insert into Production.Products failed with error ' + CAST(@errnum AS VARCHAR);
END
DECLARE @errnum AS int;
BEGIN TRAN;
SET IDENTITY_INSERT Production.Products ON;
-- Insert #1 will fail because of duplicate primary key
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(1, N'Test1: Ok categoryid', 1, 1, 18.00, 0);
SET @errnum = @@ERROR;
IF @errnum <> 0
BEGIN
IF @@TRANCOUNT > 0 ROLLBACK TRAN;
PRINT 'Insert #1 into Production.Products failed with error ' + CAST(@errnum AS VARCHAR);
END;
-- Insert #2 will succeed
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(101, N'Test2: Bad categoryid', 1, 1, 18.00, 0);
SET @errnum = @@ERROR;
IF @errnum <> 0
BEGIN
IF @@TRANCOUNT > 0 ROLLBACK TRAN;
PRINT 'Insert #2 into Production.Products failed with error ' + CAST(@errnum AS VARCHAR);
END;
SET IDENTITY_INSERT Production.Products OFF;
IF @@TRANCOUNT > 0 COMMIT TRAN;
-- Remove the inserted row
DELETE FROM Production.Products WHERE productid = 101;
PRINT 'Deleted ' + CAST(@@ROWCOUNT AS VARCHAR) + ' rows';
使用 XACT_ABORT
使用XACT_ABORT，语句中发生错误，整段语句都会中止。
SET XACT_ABORT ON;
PRINT 'Before error';
SET IDENTITY_INSERT Production.Products ON;
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(1, N'Test1: Ok categoryid', 1, 1, 18.00, 0);
SET IDENTITY_INSERT Production.Products OFF;
PRINT 'After error';
GO
PRINT 'New batch';
SET XACT_ABORT OFF;
-- Using THROW with XACT_ABORT. USE TSQL2012; GO SET XACT_ABORT ON; PRINT 'Before error'; THROW 50000, 'Error in usp_InsertCategories stored procedure', 0; PRINT 'After error'; GO PRINT 'New batch'; SET XACT_ABORT OFF;
@@ERROR第二个例子中使用XACT_ABORT以后，第二条语句这回就无效了。
DECLARE @errnum AS int;
SET XACT_ABORT ON;
BEGIN TRAN;
SET IDENTITY_INSERT Production.Products ON;
-- Insert #1 will fail because of duplicate primary key
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(1, N'Test1: Ok categoryid', 1, 1, 18.00, 0);
SET @errnum = @@ERROR;
IF @errnum <> 0
BEGIN
IF @@TRANCOUNT > 0 ROLLBACK TRAN;
PRINT 'Error in first INSERT';
END;
-- Insert #2 no longer succeeds
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(101, N'Test2: Bad categoryid', 1, 1, 18.00, 0);
SET @errnum = @@ERROR;
IF @errnum <> 0
BEGIN
-- Take actions based on the error
IF @@TRANCOUNT > 0 ROLLBACK TRAN;
PRINT 'Error in second INSERT';
END;
SET IDENTITY_INSERT Production.Products OFF;
IF @@TRANCOUNT > 0 COMMIT TRAN;
GO
DELETE FROM Production.Products WHERE productid = 101;
PRINT 'Deleted ' + CAST(@@ROWCOUNT AS VARCHAR) + ' rows';
SET XACT_ABORT OFF;
GO
SELECT XACT_STATE(), @@TRANCOUNT;
使用TRY/CATCH
格式
--Transactions extend batches BEGIN TRY BEGIN TRANSACTION INSERT INTO Sales.SalesOrderHeader... --Succeeds INSERT INTO Sales.SalesOrderDetail... --Fails COMMIT TRANSACTION -- If no errors, transaction completes END TRY BEGIN CATCH --Inserted rows still exist in Sales.SalesOrderHeader SELECT ERROR_NUMBER() ROLLBACK TRANSACTION --Any transaction work undone END CATCH;
BEGIN TRY
BEGIN TRAN;
SET IDENTITY_INSERT Production.Products ON;
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(1, N'Test1: Ok categoryid', 1, 1, 18.00, 0);
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(101, N'Test2: Bad categoryid', 1, 10, 18.00, 0);
SET IDENTITY_INSERT Production.Products OFF;
COMMIT TRAN;
END TRY
BEGIN CATCH
IF ERROR_NUMBER() = 2627 -- Duplicate key violation
BEGIN
PRINT 'Primary Key violation';
END
ELSE IF ERROR_NUMBER() = 547 -- Constraint violations
BEGIN
PRINT 'Constraint violation';
END
ELSE
BEGIN
PRINT 'Unhandled error';
END;
IF @@TRANCOUNT > 0 ROLLBACK TRANSACTION;
END CATCH;
-- revise the CATCH block using variables to capture error information and re-raise the error using RAISERROR.
USE TSQL2012;
GO
SET NOCOUNT ON;
DECLARE @error_number AS INT, @error_message AS NVARCHAR(1000), @error_severity AS INT;
BEGIN TRY
BEGIN TRAN;
SET IDENTITY_INSERT Production.Products ON;
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(1, N'Test1: Ok categoryid', 1, 1, 18.00, 0);
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(101, N'Test2: Bad categoryid', 1, 10, 18.00, 0);
SET IDENTITY_INSERT Production.Products OFF;
COMMIT TRAN;
END TRY
BEGIN CATCH
SELECT XACT_STATE() as 'XACT_STATE', @@TRANCOUNT as '@@TRANCOUNT';
SELECT @error_number = ERROR_NUMBER(), @error_message = ERROR_MESSAGE(), @error_severity = ERROR_SEVERITY();
RAISERROR (@error_message, @error_severity, 1);
IF @@TRANCOUNT > 0 ROLLBACK TRANSACTION;
END CATCH;
-- use a THROW statement without parameters re-raise (re-throw) the original error message and send it back to the client.
USE TSQL2012;
GO
BEGIN TRY
BEGIN TRAN;
SET IDENTITY_INSERT Production.Products ON;
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(1, N'Test1: Ok categoryid', 1, 1, 18.00, 0);
INSERT INTO Production.Products(productid, productname, supplierid, categoryid, unitprice, discontinued)
VALUES(101, N'Test2: Bad categoryid', 1, 10, 18.00, 0);
SET IDENTITY_INSERT Production.Products OFF;
COMMIT TRAN;
END TRY
BEGIN CATCH
SELECT XACT_STATE() as 'XACT_STATE', @@TRANCOUNT as '@@TRANCOUNT';
IF @@TRANCOUNT > 0 ROLLBACK TRANSACTION;
THROW;
END CATCH;
GO
SELECT XACT_STATE() as 'XACT_STATE', @@TRANCOUNT as '@@TRANCOUNT';
现实中的事务语句
删除
--删除
CREATE PROCEDURE [dbo].[Students_Delete](@ID int)
WITH EXECUTE AS CALLER
AS
BEGIN
--Check to make sure the ID does exist
--If not does, return error
DECLARE @existing AS int = 0
SELECT @existing = count(ID)
FROM Students
WHERE ID = @ID
IF @existing <> 1
BEGIN
RAISERROR ('ID does not exist', 1, 1)
RETURN 0
END
--Attempt Delete
DELETE FROM [dbo].[Students]
WHERE ID = @ID
--check to see if update occured
--and return status
IF @@ROWCOUNT = 1
BEGIN
INSERT INTO StudentDeleteLog
VALUES (suser_sname(), @ID, getdate())
RETURN 1
END
ELSE
RETURN 0
END
GO
更新
CREATE PROCEDURE [dbo].[Students_Update]
( @ID int,
@LASTNAME varchar(50),
@FIRSTNAME varchar(50),
@STATE varchar(50),
@PHONE varchar(50),
@EMAIL varchar(50),
@GRADYEAR int,
@GPA decimal(20,10),
@PROGRAM varchar(50),
@NEWSLETTER bit
)
AS
BEGIN
--Check to make sure the ID does exist
--If not does, return error
DECLARE @existing AS int = 0
SELECT @existing = count(ID)
FROM Students
WHERE ID = @ID
IF @existing <> 1
BEGIN
RAISERROR ('ID does not exist', 1, 1)
RETURN 0
END
--Can not subscribe to newsletter if email is null
IF (@email IS NULL)
SET @NEWSLETTER = 0
--Attempt Update
UPDATE [dbo].[Students]
SET [LASTNAME] = @LASTNAME
,[FIRSTNAME] = @FIRSTNAME
,[STATE] = @STATE
,[PHONE] = @PHONE
,[EMAIL] = @EMAIL
,[GRADYEAR] = @GRADYEAR
,[GPA] = @GPA
,[PROGRAM] = @PROGRAM
,[NEWSLETTER] = @NEWSLETTER
WHERE ID = @ID
--check to see if update occured
--and return status
IF @@ROWCOUNT = 1
RETURN 1
ELSE
RETURN 0
END
GO
银行取钱
BEGIN TRAN;
IF NOT EXISTS (
SELECT * FROM Accounts WITH(UPDLOCK) --只有当前的事务可以查看
WHERE AccountID = 47387438 AND Balance >= 400
)
BEGIN
ROOLBACK TRAN;
THROW 50000,'Tobias is too poor',1;
END
UPDATE Accounts SET
Balance -=400
WHERE AccountID = 47387438;
COMMIT TRAN;
--银行取钱高效版本
BEGIN TRAN;
UPDATE Accounts SET
Balance -= 400
WHERE AccountID = 47387438 AND Balance >= 400
IF(@@ROWCOUNT <> 1)
BEGIN
ROLLBACK TRAN;
THROW 50000,'Tobias is too poor ',1;
END
COMMIT TRAN;
参考文档
Database Engine Error Severities
https://msdn.microsoft.com/en-us/library/ms164086.aspx
SET XACT_ABORT (Transact-SQL)
https://msdn.microsoft.com/zh-tw/library/ms188792.aspx