一个容易忽视的存储过程问题_数据库技巧

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.

出处:jackyrong BLOG