SQL Server:错误处理及事务控制

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