Question

我想更新三列，即LCID，LCNo，AmendmentStatus，它们是从PI Table中选择的，所以我写下了Update Query，它们是成功执行的：

UPDATE  #TempTableOne  
    SET     
            LCID=(SELECT ISNULL(ExportLCID,0) FROM ExportLC WHERE ExportLCID= (SELECT LCID FROM [PI] WHERE PIID=(SELECT PIID FROM Job WHERE JobID=TT.OrderID))),
            LCNo=(SELECT ISNULL(ExportLCNo,'') FROM ExportLC WHERE ExportLCID= (SELECT LCID FROM [PI] WHERE PIID=(SELECT PIID FROM Job WHERE JobID=TT.OrderID))),
            AmendmentStatus=(SELECT AmendmentStatus FROM ExportLC WHERE ExportLCID= (SELECT LCID FROM [PI] WHERE PIID=(SELECT PIID FROM Job WHERE JobID=TT.OrderID))),      

    FROM    #TempTableOne  AS TT
    WHERE TT.OrderType=3

但更新查询是否可能执行单个查询，如：

Update  #TempTableOne    
   SET  SELECT LCID = ISNULL(ExportLCID,0) ,
        LCNo=ISNULL(ExportLCNo,''), 
        AmendmentStatus=AmendmentStatus 
  FROM  ExportLC 
  WHERE ExportLCID = (SELECT LCID 
                        FROM [PI] 
                       WHERE PIID=(SELECT PIID 
                                     FROM Job 
                                     WHERE JobID=TT.OrderID
                                   )
                       )
               )

因为我想加快我的查询

Answer 1

将您的查询更改为使用JOINS可以加快速度：

Update  #TempTableOne    
   SET  LCID = ISNULL(lc.ExportLCID,0) ,
        LCNo=ISNULL(lc.ExportLCNo,''), 
        AmendmentStatus=lc.AmendmentStatus 
  FROM #TempTableOne tt  
  JOIN  Job on Job.JobID = TT.OrderID
  JOIN  [PI] on [PI].PIID = Job.PIID
  JOIN ExportLC lc on [PI].LCID = lc.ExportLCID

具有多个列的SQL Update Query，其值从另一个表作为单个查询获取

1 个答案: