SQL Update查询，具有多个列，这些列的值作为单个查询从另一个表中获取

我想更新从PI表中选择的三列，即LCID、LCNo、AmendmentStatus，因此我编写了以下更新查询，这些查询已成功执行：

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

但是更新查询是否可以执行如下单个查询：

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

将查询更改为关闭连接应该会使查询速度更快：

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 

---

将查询更改为关闭联接将使其速度更快：

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 

---

如果我使用如下聚合函数：PIQty=SELECT ISNULLSUMQty，0 FROM PIProducts，其中PIID=SELECT PIID FROM Job，其中JobID=TT.OrderID，ProductID=TT.ProductID，-samconcejqy=SELECT isnullsumadqty，0 FROM PIProducts，其中PIID=SELECT PIID FROM Job，其中JobID=TT.OrderID，ProductID=TT.ProductID，-samconcejvalue=SELECT ISNULLSUMAdjValue，0来自PIProducts，其中PIID=SELECT PIID来自JobID=TT.OrderID和ProductID=TT.ProductID的作业，如果我使用聚合函数，如：PIQty=SELECT ISNULLSUMQty，0来自PIProducts，其中PIID=SELECT PIID来自JobID=TT.OrderID和ProductID=TT.ProductID的作业，-SAMCONCEJQTY=SELECT ISNULLSUMAdjQty，0来自PIProducts，其中PIID=SELECT PIID来自JobID=TT.OrderID且ProductID=TT.ProductID，-SAMCONCEJVALUE=SELECT ISNULLSUMAdjValue，0来自PIProducts，其中PIID=SELECT PIID来自JobID=TT.OrderID且ProductID=TT.ProductID，