精品国产亚洲一区二区三区,男女作爱在线观看免费网站,欧美的又大又长做禁片A片,97国产精品人妻无码久久久

返回最后執(zhí)行的 Transact-SQL 語(yǔ)句的錯(cuò)誤代碼。

語(yǔ)法

@@ERROR

返回類型

integer

注釋

當(dāng) Microsoft® SQL Server™ 完成 Transact-SQL 語(yǔ)句的執(zhí)行時(shí)，如果語(yǔ)句執(zhí)行成功，則 @@ERROR 設(shè)置為 0。若出現(xiàn)一個(gè)錯(cuò)誤，則返回一條錯(cuò)誤信息。@@ERROR 返回此錯(cuò)誤信息代碼，直到另一條 Transact-SQL 語(yǔ)句被執(zhí)行。您可以在 sysmessages 系統(tǒng)表中查看與 @@ERROR 錯(cuò)誤代碼相關(guān)的文本信息。

由于 @@ERROR 在每一條語(yǔ)句執(zhí)行后被清除并且重置，應(yīng)在語(yǔ)句驗(yàn)證后立即檢查它，或?qū)⑵浔４娴揭粋€(gè)局部變量中以備事后查看。

示例

A.用 @@ERROR 檢測(cè)一個(gè)特定錯(cuò)誤

下面的示例用 @@ERROR 在一個(gè) UPDATE 語(yǔ)句中檢測(cè)限制檢查沖突（錯(cuò)誤 #547）。

USE pubs
GO
UPDATE authors SET au_id = '172 32 1176'
WHERE au_id = "172-32-1176"

IF @@ERROR = 547
   print "A check constraint violation occurred"

B.用 @@ERROR 有條件地退出一個(gè)過(guò)程

在此示例中，IF...ELSE 語(yǔ)句在存儲(chǔ)過(guò)程中的 INSERT 語(yǔ)句后檢測(cè) @@ERROR。@@ERROR 變量的值將決定傳給調(diào)用程序的返回值，以指示此過(guò)程的成功與失敗。

USE pubs
GO

-- Create the procedure.
CREATE PROCEDURE add_author 
@au_id varchar(11),@au_lname varchar(40),
@au_fname varchar(20),@phone char(12),
@address varchar(40) = NULL,@city varchar(20) = NULL,
@state char(2) = NULL,@zip char(5) = NULL,
@contract bit = NULL
AS

-- Execute the INSERT statement.
INSERT INTO authors
(au_id,  au_lname, au_fname, phone, address, 
 city, state, zip, contract) values
(@au_id,@au_lname,@au_fname,@phone,@address,
 @city,@state,@zip,@contract)

-- Test the error value.
IF @@ERROR <> 0 
BEGIN
   -- Return 99 to the calling program to indicate failure.
   PRINT "An error occurred loading the new author information"
   RETURN(99)
END
ELSE
BEGIN
   -- Return 0 to the calling program to indicate success.
   PRINT "The new author information has been loaded"
   RETURN(0)
END
GO

C.用 @@ERROR 檢測(cè)幾條語(yǔ)句的成功

下面的示例取決于 INSERT 和 DELETE 語(yǔ)句的成功操作。局部變量在兩條語(yǔ)句后均被設(shè)置為 @@ERROR 的值，并且用于此操作的共享錯(cuò)誤處理例程中。

USE pubs
GO
DECLARE @del_error int, @ins_error int
-- Start a transaction.
BEGIN TRAN

-- Execute the DELETE statement.
DELETE authors
WHERE au_id = '409-56-7088'

-- Set a variable to the error value for 
-- the DELETE statement.
SELECT @del_error = @@ERROR

-- Execute the INSERT statement.
INSERT authors
   VALUES('409-56-7008', 'Bennet', 'Abraham', '415 658-9932',
   '6223 Bateman St.', 'Berkeley', 'CA', '94705', 1)
-- Set a variable to the error value for 
-- the INSERT statement.
SELECT @ins_error = @@ERROR

-- Test the error values.
IF @del_error = 0 AND @ins_error = 0
BEGIN
   -- Success. Commit the transaction.
   PRINT "The author information has been replaced"    
   COMMIT TRAN
END
ELSE
BEGIN
   -- An error occurred. Indicate which operation(s) failed
   -- and roll back the transaction.
   IF @del_error <> 0 
      PRINT "An error occurred during execution of the DELETE 
      statement." 

   IF @ins_error <> 0
      PRINT "An error occurred during execution of the INSERT 
      statement." 

   ROLLBACK TRAN
END
GO

D. 與 @@ROWCOUNT 一同使用 @@ERROR

下面的示例用 @@ERROR 和 @@ROWCOUNT 驗(yàn)證一條 UPDATE 語(yǔ)句的操作。為任何可能出現(xiàn)的錯(cuò)誤而檢驗(yàn) @@ERROR 的值，而用 @@ROWCOUNT 保證更新已成功應(yīng)用于表中的某行。

USE pubs
GO
CREATE PROCEDURE change_publisher
@title_id tid, 
@new_pub_id char(4) 
AS

-- Declare variables used in error checking.
DECLARE @error_var int, @rowcount_var int

-- Execute the UPDATE statement.
UPDATE titles SET pub_id = @new_pub_id 
WHERE title_id = @title_id 

-- Save the @@ERROR and @@ROWCOUNT values in local 
-- variables before they are cleared.
SELECT @error_var = @@ERROR, @rowcount_var = @@ROWCOUNT

-- Check for errors. If an invalid @new_pub_id was specified
-- the UPDATE statement returns a foreign-key violation error #547.
IF @error_var <> 0
BEGIN
   IF @error_var = 547
   BEGIN
      PRINT "ERROR: Invalid ID specified for new publisher"
      RETURN(1)
   END
   ELSE
   BEGIN
      PRINT "ERROR: Unhandled error occurred"
      RETURN(2)
   END
END

-- Check the rowcount. @rowcount_var is set to 0 
-- if an invalid @title_id was specified.
IF @rowcount_var = 0 
BEGIN
   PRINT "Warning: The title_id specified is not valid"
   RETURN(1)
END
ELSE
BEGIN
   PRINT "The book has been updated with the new publisher"
   RETURN(0)
END
GO