sql server 2005中新增加的try catch學(xué)習(xí)
sql server 2005中新增加的try catch,可以很容易捕捉異常了,今天大概學(xué)習(xí)看了下,歸納下要點(diǎn)如下
基本用法BEGIN TRY {; sql_statement | statement_block; }END TRYBEGIN CATCH {; sql_statement | statement_block }END CATCH,和普通語(yǔ)言的異常處理用法差不多,但要注意的是,SQL SERVER只捕捉那些不是嚴(yán)重的異常,當(dāng)比如數(shù)據(jù)庫(kù)不能連接等這類異常時(shí),是不能捕捉的一個(gè)例子:BEGIN TRY DECLARE @X INT -- Divide by zero to generate Error SET @X = 1/0 PRINT 'Command after error in TRY block'END TRYBEGIN CATCH PRINT 'Error Detected'END CATCHPRINT 'Command after TRY/CATCH blocks'; 另外try catch可以嵌套Begin TRY delete from GrandParent where Name = 'John Smith' print 'GrandParent deleted successfully'End TryBegin Catch Print 'Error Deleting GrandParent Record' Begin Try delete from Parent where GrandParentID = (select distinct ID from GrandParent where Name = 'John Smith') Print 'Parent Deleted Successfully' End Try Begin Catch print 'Error Deleting Parent' Begin Try delete from child where ParentId = (select distinct ID from Parent where GrandParentID = (select distinct ID from GrandParent where Name = 'John Smith')) print 'Child Deleted Successfully' End Try Begin Catch Print 'Error Deleting Child' End Catch End CatchEnd Catch另外,SQL SERVER 2005在異常機(jī)制中,提供了error類的方法方便調(diào)試,現(xiàn)摘抄如下,比較簡(jiǎn)單,不予以解釋ERROR_NUMBER(): Returns a number associated with the error.ERROR_SEVERITY(): Returns the severity of the error.ERROR_STATE(): Returns the error state number associated with the error.ERROR_PROCEDURE(): Returns the name of the stored procedure or trigger in which the error occurred.ERROR_LINE(): Returns the line number inside the failing routine that caused the error. ERROR_MESSAGE(): Returns the complete text of the error message. The text includes the values supplied for any substitutable parameters, such as lengths, object names, or times. 最后舉例子如下,使用了error類的方法BEGIN TRY DECLARE @X INT -- Divide by zero to generate Error SET @X = 1/0 PRINT 'Command after error in TRY block'END TRYBEGIN CATCH PRINT 'Error Detected' SELECT ERROR_NUMBER() ERNumber, ERROR_SEVERITY() Error_Severity, ERROR_STATE() Error_State, ERROR_PROCEDURE() Error_Procedure, ERROR_LINE() Error_Line, ERROR_MESSAGE() Error_MessageEND CATCHPRINT 'Command after TRY/CATCH blocks'最后輸出Error DetectedErr_Num Err_Sev Err_State Err_Proc;;Err_Line; Err_Msg------- ------- --------- -------------------- --------- --------------------------------8134;;;;;16; 1 NULL 4;;;;;Divide by zero error encountered.
