Question

您好我正在研究sql存储过程。目前，检查服务器上的磁盘空间量，然后在一定量（100MB）下向用户发送电子邮件通知。我只是想对下面的一些代码做一些澄清：

 SET @tableHTML = 'This is to notify you that Insufficient disk space encountered
                  in' + @DiskDrive + ' Drive' + '('+ + ')' + 'in SQLCircuit

我只是在找人解释'（'''''''的作用。完整代码如下：

CREATE PROCEDURE [dbo].[GetServerSpaceStatus]
 AS
 BEGIN
       SET NOCOUNT ON

       DECLARE              @sErrorMessage       AS NVARCHAR(255)
       DECLARE              @lErrorMessageID     AS INT
       DECLARE              @lReturnCode         AS INT
       DECLARE              @sMessage            AS NVARCHAR(4000)   
       DECLARE              @lIdentity           AS INT
       DECLARE              @DiskDrive           AS NVARCHAR(100)
       DECLARE              @DiskSpace           AS INT
       DECLARE              @SUBJECTMESSAGE NVARCHAR(500)
       DECLARE              @tableHTML NVARCHAR(500)

BEGIN TRY

       --Declaring table variable for storing Disk space information
       DECLARE @DiskFreeSpace AS TABLE
       (
        Drive CHAR(1),
        MB_Free INT
       )
       --Inserting disk space availability details into table variable
       INSERT INTO @DiskFreeSpace
       EXEC xp_fixeddrives

       --Storing drive name and free space(in MB) in variable.
       --Creteria for insufficient disk space equal or less than 100 MB
       SELECT  @DiskDrive= Drive ,
               @DiskSpace = MB_Free
       FROM @DiskFreeSpace
       WHERE MB_Free < 100

SET @SUBJECTMESSAGE= 'Production Support Mail: Insufficent Disk Space in ' +
@DiskDrive + ' Drive in SQLCircuit Blogspot Server'
SET @tableHTML = 'This is to notify you that Insufficient disk space encountered
                  in' + @DiskDrive + ' Drive' + '('+ + ')' + 'in         SQLCircuit
Blogspot Server, Please take necessary action to avoid any further issues' + 
CHAR(4) + 'Thanks,' + CHAR(4) +'SQLCircuit Team'

      --Sending Mail       
      EXEC msdb.dbo.sp_send_dbmail
                     @recipients='sqlcircuit@gmail.com',   
                     @subject = @SUBJECTMESSAGE,   
                     @Profile_Name='sqlcircuit',  --Profile of SMTP Server 
                     @body =  @tableHTML,   
                     @body_format = 'HTML' ;

      SET @lReturnCode = 0

END TRY 
       BEGIN CATCH  
             --logging Error information
             INSERT INTO [dbo].[ErrorLog]
                      ([MessageID],[ErrorNumber],[ErrorSeverity],[ErrorState],
                      [ErrorProcedure],[ErrorLine],[ErrorMessage],[CreatedBy],
                      [CreatedDate])                    
             VALUES
            (1,ERROR_NUMBER(),ERROR_SEVERITY(),ERROR_STATE(),ISNULL(ERROR_PROCEDURE(), '-
            '),ERROR_LINE(),ERROR_MESSAGE(),'',GETDATE())  

END CATCH 
       RETURN @lReturnCode
       SET NOCOUNT OFF           
END

Answer 1

我愿意打赌这是一个错字。也许原作者打算在那时将变量的内容插入到消息中，而忘记这样做。

SQL Server将第一个+解释为字符串连接运算符，将第二个+解释为后面的字符串上的unary plus。该运算符仅适用于数字操作数，但在此上下文中仍允许使用它。微软在TechNet上发表声明here，他们声称这是一个错误，但是一个好的错误，并且由于向后兼容性问题，他们并不打算修复它。

通知程序通知磁盘空间量？

1 个答案: