在 Transact-SQL 中使用 TRY...CATCH

在 Transact-SQL 中使用 TRY...CATCH

BEGIN TRY
SELECT *
FROM sys.messages
WHERE message_id = 21;
END TRY
GO
-- The previous GO breaks the script into two batches,
-- generating syntax errors. The script runs if this GO
-- is removed.
BEGIN CATCH
SELECT ERROR_NUMBER() AS ErrorNumber;
END CATCH;
GO

注意
如果在 TRY 块的作用域内执行分布式事务且发生错误，执行将传递到关联的 CATCH 块。分布式事务进入不可提交状态。CATCH 块中的执行可能由管理分布式事务的 Microsoft 分布式事务处理协调器中断。发生错误时，MS DTC 将异步通知参与分布式事务的所有服务器，并终止分布式事务中涉及的所有任务。此类通知以关注消息的形式发送（TRY...CATCH 构造不处理此类通知），批处理将被终止。当批处理完成运行时，数据库引擎将回滚所有不可提交的活动事务。如果事务进入不可提交状态时未发送错误消息，则当批处理完成时，将向客户端应用程序发送错误消息，该消息指示检测到或回滚了一个不可提交的事务。有关分布式事务的详细信息，请参阅分布式事务（数据库引擎）。

错误函数

USE AdventureWorks2008R2;
GO

-- Verify that the stored procedure does not exist.
IF OBJECT_ID ('usp_GetErrorInfo', 'P') IS NOT NULL
DROP PROCEDURE usp_GetErrorInfo;
GO

-- Create a procedure to retrieve error information.
CREATE PROCEDURE usp_GetErrorInfo
AS
SELECT
ERROR_NUMBER() AS ErrorNumber,
ERROR_SEVERITY() AS ErrorSeverity,
ERROR_STATE() as ErrorState,
ERROR_PROCEDURE() as ErrorProcedure,
ERROR_LINE() as ErrorLine,
ERROR_MESSAGE() as ErrorMessage;
GO

BEGIN TRY
-- Generate divide-by-zero error.
SELECT 1/0;
END TRY
BEGIN CATCH
-- Execute the error retrieval routine.
EXECUTE usp_GetErrorInfo;
END CATCH;
GO

编译错误和语句级重新编译错误

USE AdventureWorks2008R2;
GO

BEGIN TRY
-- This PRINT statement will not run because the batch
-- does not begin execution.
PRINT N'Starting execution';

-- This SELECT statement contains a syntax error that
-- stops the batch from compiling successfully.
SELECT ** FROM HumanResources.Employee;
END TRY
BEGIN CATCH
SELECT
ERROR_NUMBER() AS ErrorNumber,
ERROR_MESSAGE() AS ErrorMessage;
END CATCH;
GO

USE AdventureWorks2008R2;
GO

BEGIN TRY
-- This PRINT statement will run because the error
-- occurs at the SELECT statement.
PRINT N'Starting execution';

-- This SELECT statement will generate an object name
-- resolution error because the table does not exist.
SELECT * FROM NonExistentTable;
END TRY
BEGIN CATCH
SELECT
ERROR_NUMBER() AS ErrorNumber,
ERROR_MESSAGE() AS ErrorMessage;
END CATCH;
GO

USE AdventureWorks2008R2;
GO

-- Verify that the stored procedure does not already exist.
IF OBJECT_ID ('usp_MyError', 'P') IS NOT NULL
DROP PROCEDURE usp_MyError;
GO

CREATE PROCEDURE usp_MyError
AS
-- This SELECT statement will generate
-- an object name resolution error.
SELECT * FROM NonExistentTable;
GO

BEGIN TRY
-- Run the stored procedure.
EXECUTE usp_MyError;
END TRY
BEGIN CATCH
SELECT
ERROR_NUMBER() AS ErrorNumber,
ERROR_MESSAGE() AS ErrorMessage;
END CATCH;
GO

ErrorNumber ErrorMessage
----------- ---------------------------------------
208         Invalid object name 'NonExistentTable'.

不可提交的事务

USE AdventureWorks2008R2;
GO

-- Verify that the table does not exist.
IF OBJECT_ID (N'my_books', N'U') IS NOT NULL
DROP TABLE my_books;
GO

-- Create table my_books.
CREATE TABLE my_books
(
Isbn        int PRIMARY KEY,
Title       NVARCHAR(100)
);
GO

BEGIN TRY
BEGIN TRANSACTION;
-- This statement will generate an error because the
-- column author does not exist in the table.
ALTER TABLE my_books
DROP COLUMN author;
-- If the DDL statement succeeds, commit the transaction.
COMMIT TRANSACTION;
END TRY
BEGIN CATCH
SELECT
ERROR_NUMBER() as ErrorNumber,
ERROR_MESSAGE() as ErrorMessage;

-- Test XACT_STATE for 1 or -1.
-- XACT_STATE = 0 means there is no transaction and
-- a commit or rollback operation would generate an error.

-- Test whether the transaction is uncommittable.
IF (XACT_STATE()) = -1
BEGIN
PRINT
N'The transaction is in an uncommittable state. ' +
'Rolling back transaction.'
ROLLBACK TRANSACTION;
END;

-- Test whether the transaction is active and valid.
IF (XACT_STATE()) = 1
BEGIN
PRINT
N'The transaction is committable. ' +
'Committing transaction.'
COMMIT TRANSACTION;
END;
END CATCH;
GO

处理死锁

USE AdventureWorks2008R2;
GO

-- Verify that the table does not exist.
IF OBJECT_ID (N'my_sales',N'U') IS NOT NULL
DROP TABLE my_sales;
GO

-- Create and populate the table for deadlock simulation.
CREATE TABLE my_sales
(
Itemid       INT PRIMARY KEY,
Sales        INT not null
);
GO

INSERT my_sales (itemid, sales) VALUES (1, 1);
INSERT my_sales (itemid, sales) VALUES (2, 1);
GO

-- Verify that the stored procedure for error printing
-- does not exist.
IF OBJECT_ID (N'usp_MyErrorLog',N'P') IS NOT NULL
DROP PROCEDURE usp_MyErrorLog;
GO

-- Create a stored procedure for printing error information.
CREATE PROCEDURE usp_MyErrorLog
AS
PRINT
'Error ' + CONVERT(VARCHAR(50), ERROR_NUMBER()) +
', Severity ' + CONVERT(VARCHAR(5), ERROR_SEVERITY()) +
', State ' + CONVERT(VARCHAR(5), ERROR_STATE()) +
', Line ' + CONVERT(VARCHAR(5), ERROR_LINE());
PRINT
ERROR_MESSAGE();
GO

USE AdventureWorks2008R2;
GO

-- Declare and set variable
-- to track number of retries
-- to try before exiting.
DECLARE @retry INT;
SET @retry = 5;

-- Keep trying to update
-- table if this task is
-- selected as the deadlock
-- victim.
WHILE (@retry > 0)
BEGIN
BEGIN TRY
BEGIN TRANSACTION;

UPDATE my_sales
SET sales = sales + 1
WHERE itemid = 1;

WAITFOR DELAY '00:00:13';

UPDATE my_sales
SET sales = sales + 1
WHERE itemid = 2;

SET @retry = 0;

COMMIT TRANSACTION;
END TRY
BEGIN CATCH
-- Check error number.
-- If deadlock victim error,
-- then reduce retry count
-- for next update retry.
-- If some other error
-- occurred, then exit
-- retry WHILE loop.
IF (ERROR_NUMBER() = 1205)
SET @retry = @retry - 1;
ELSE
SET @retry = -1;

-- Print error information.
EXECUTE usp_MyErrorLog;

IF XACT_STATE() <> 0
ROLLBACK TRANSACTION;
END CATCH;
END; -- End WHILE loop.
GO

USE AdventureWorks2008R2;
GO

-- Declare and set variable
-- to track number of retries
-- to try before exiting.
DECLARE @retry INT;
SET @retry = 5;

--Keep trying to update
-- table if this task is
-- selected as the deadlock
-- victim.
WHILE (@retry > 0)
BEGIN
BEGIN TRY
BEGIN TRANSACTION;

UPDATE my_sales
SET sales = sales + 1
WHERE itemid = 2;

WAITFOR DELAY '00:00:07';

UPDATE my_sales
SET sales = sales + 1
WHERE itemid = 1;

SET @retry = 0;

COMMIT TRANSACTION;
END TRY
BEGIN CATCH
-- Check error number.
-- If deadlock victim error,
-- then reduce retry count
-- for next update retry.
-- If some other error
-- occurred, then exit
-- retry WHILE loop.
IF (ERROR_NUMBER() = 1205)
SET @retry = @retry - 1;
ELSE
SET @retry = -1;

-- Print error information.
EXECUTE usp_MyErrorLog;

IF XACT_STATE() <> 0
ROLLBACK TRANSACTION;
END CATCH;
END; -- End WHILE loop.
GO

使用 RAISERROR 的 TRY...CATCH

注意
RAISERROR 仅能生成状态从 1 到 127 的错误。由于数据库引擎可能引发状态为 0 的错误，因此，建议您先检查由 ERROR_STATE 返回的错误状态，然后将它作为一个值传递给状态参数 RAISERROR。

USE AdventureWorks2008R2;
GO

-- Verify that stored procedure does not exist.
IF OBJECT_ID (N'usp_RethrowError',N'P') IS NOT NULL
DROP PROCEDURE usp_RethrowError;
GO

-- Create the stored procedure to generate an error using
-- RAISERROR. The original error information is used to
-- construct the msg_str for RAISERROR.
CREATE PROCEDURE usp_RethrowError AS
-- Return if there is no error information to retrieve.
IF ERROR_NUMBER() IS NULL
RETURN;

DECLARE
@ErrorMessage    NVARCHAR(4000),
@ErrorNumber     INT,
@ErrorSeverity   INT,
@ErrorState      INT,
@ErrorLine       INT,
@ErrorProcedure  NVARCHAR(200);

-- Assign variables to error-handling functions that
-- capture information for RAISERROR.
SELECT
@ErrorNumber = ERROR_NUMBER(),
@ErrorSeverity = ERROR_SEVERITY(),
@ErrorState = ERROR_STATE(),
@ErrorLine = ERROR_LINE(),
@ErrorProcedure = ISNULL(ERROR_PROCEDURE(), '-');

-- Build the message string that will contain original
-- error information.
SELECT @ErrorMessage =
N'Error %d, Level %d, State %d, Procedure %s, Line %d, ' +
'Message: '+ ERROR_MESSAGE();

-- Raise an error: msg_str parameter of RAISERROR will contain
-- the original error information.
RAISERROR
(
@ErrorMessage,
@ErrorSeverity,
1,
@ErrorNumber,    -- parameter: original error number.
@ErrorSeverity,  -- parameter: original error severity.
@ErrorState,     -- parameter: original error state.
@ErrorProcedure, -- parameter: original error procedure name.
@ErrorLine       -- parameter: original error line number.
);
GO

-- Verify that stored procedure does not exist.
IF OBJECT_ID (N'usp_GenerateError',N'P') IS NOT NULL
DROP PROCEDURE usp_GenerateError;
GO

-- Create a stored procedure that generates a constraint violation
-- error. The error is caught by the CATCH block where it is
-- raised again by executing usp_RethrowError.
CREATE PROCEDURE usp_GenerateError
AS
BEGIN TRY
-- A FOREIGN KEY constraint exists on the table. This
-- statement will generate a constraint violation error.
DELETE FROM Production.Product
WHERE ProductID = 980;
END TRY
BEGIN CATCH
-- Call the procedure to raise the original error.
EXEC usp_RethrowError;
END CATCH;
GO

-- In the following batch, an error occurs inside
-- usp_GenerateError that invokes the CATCH block in
-- usp_GenerateError. RAISERROR inside this CATCH block
-- generates an error that invokes the outer CATCH
-- block in the calling batch.
BEGIN TRY  -- outer TRY
-- Call the procedure to generate an error.
EXECUTE usp_GenerateError;
END TRY
BEGIN CATCH  -- Outer CATCH
SELECT
ERROR_NUMBER() as ErrorNumber,
ERROR_MESSAGE() as ErrorMessage;
END CATCH;
GO

更改执行流

dbo.ErrorLog 表

dbo.uspLogError

CREATE PROCEDURE [dbo].[uspLogError]
@ErrorLogID [int] = 0 OUTPUT  -- Contains the ErrorLogID of the row inserted
-- by uspLogError in the ErrorLog table.

AS
BEGIN
SET NOCOUNT ON;

-- Output parameter value of 0 indicates that error
-- information was not logged.
SET @ErrorLogID = 0;

BEGIN TRY
-- Return if there is no error information to log.
IF ERROR_NUMBER() IS NULL
RETURN;

-- Return if inside an uncommittable transaction.
-- Data insertion/modification is not allowed when
-- a transaction is in an uncommittable state.
IF XACT_STATE() = -1
BEGIN
PRINT 'Cannot log error since the current transaction is in an uncommittable state. '
+ 'Rollback the transaction before executing uspLogError in order to successfully log error information.';
RETURN;
END;

INSERT [dbo].[ErrorLog]
(
[UserName],
[ErrorNumber],
[ErrorSeverity],
[ErrorState],
[ErrorProcedure],
[ErrorLine],
[ErrorMessage]
)
VALUES
(
CONVERT(sysname, CURRENT_USER),
ERROR_NUMBER(),
ERROR_SEVERITY(),
ERROR_STATE(),
ERROR_PROCEDURE(),
ERROR_LINE(),
ERROR_MESSAGE()
);

-- Pass back the ErrorLogID of the row inserted
SELECT @ErrorLogID = @@IDENTITY;
END TRY
BEGIN CATCH
PRINT 'An error occurred in stored procedure uspLogError: ';
EXECUTE [dbo].[uspPrintError];
RETURN -1;
END CATCH
END;

dbo.uspPrintError

CREATE PROCEDURE [dbo].[uspPrintError]
AS
BEGIN
SET NOCOUNT ON;

-- Print error information.
PRINT 'Error ' + CONVERT(varchar(50), ERROR_NUMBER()) +
', Severity ' + CONVERT(varchar(5), ERROR_SEVERITY()) +
', State ' + CONVERT(varchar(5), ERROR_STATE()) +
', Procedure ' + ISNULL(ERROR_PROCEDURE(), '-') +
', Line ' + CONVERT(varchar(5), ERROR_LINE());
PRINT ERROR_MESSAGE();
END;

错误处理示例

USE AdventureWorks2008R2;
GO

-- Variable to store ErrorLogID value of the row
-- inserted in the ErrorLog table by uspLogError
DECLARE @ErrorLogID INT;

BEGIN TRY
BEGIN TRANSACTION;

-- A FOREIGN KEY constraint exists on this table. This
-- statement will generate a constraint violation error.
DELETE FROM Production.Product
WHERE ProductID = 980;

-- If the delete operation succeeds, commit the transaction.
COMMIT TRANSACTION;
END TRY
BEGIN CATCH
-- Call procedure to print error information.
EXECUTE dbo.uspPrintError;

-- Roll back any active or uncommittable transactions before
-- inserting information in the ErrorLog.
IF XACT_STATE() <> 0
BEGIN
ROLLBACK TRANSACTION;
END

EXECUTE dbo.uspLogError @ErrorLogID = @ErrorLogID OUTPUT;
END CATCH;

-- Retrieve logged error information.
SELECT * FROM dbo.ErrorLog WHERE ErrorLogID = @ErrorLogID;
GO

嵌套错误处理示例

BEGIN TRY
BEGIN TRY
SELECT CAST('invalid_date' AS datetime)
END TRY
BEGIN CATCH
PRINT 'Inner TRY error number: ' +
CONVERT(varchar,ERROR_NUMBER()) + ' on line: ' +
CONVERT(varchar, ERROR_LINE())
END CATCH
SELECT CAST('invalid_int' AS int)
END TRY
BEGIN CATCH
PRINT 'Outer TRY error mumber: ' + CONVERT(varchar,ERROR_NUMBER())+
' on line: ' + CONVERT(varchar, ERROR_LINE())
END CATCH