server
sql server 2005中新增加的try catch，可以很容易捕捉异常了，今天大概学习看了下，归纳下要点如下
基本用法BEGIN TRY
{ sql_statement |
statement_block }
END TRY
BEGIN CATCH
{ sql_statement |
statement_block }
END CATCH
，和普通语言的异常处理用法差不多，但要注意的是，SQL SERVER只捕捉那些不是严重的异常，当比如数据库不能连接等这类异常时，是不能捕捉的一个例子：BEGIN TRY
DECLARE @X INT
-- Divide by zero to generate Error
SET @X = 1/0
PRINT 'Command after error in TRY block'
END TRY
BEGIN CATCH
PRINT 'Error Detected'
END CATCH
PRINT '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 Try
Begin 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 Catch
End Catch
另外，SQL SERVER 2005在异常机制中，提供了error类的方法方便调试，现摘抄如下，比较简单，不予以解释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. 最后举例子如下，使用了error类的方法BEGIN TRY
DECLARE @X INT
-- Divide by zero to generate Error
SET @X = 1/0
PRINT 'Command after error in TRY block'
END TRY
BEGIN 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_Message
END CATCH
PRINT 'Command after TRY/CATCH blocks'
最后输出Error Detected
Err_Num Err_Sev Err_State Err_Proc Err_Line Err_Msg
------- ------- --------- -------------------- --------- --------------------------------
8134 16 1 NULL 4 Divide by zero error encountered.