当我在查询加入中使用外部应用代替左连接时？ [英] When I use Outer Apply in place of Left Join in Query Joining ?

问题描述

嗨朋友们，



我可以用OUTER APPLY代替Left Join



代码如下：

Hi Friends,

where i can use OUTER APPLY in place of Left Join

some code as below:

OUTER APPLY
  (
      SELECT IPO.PurchaseOrderID,ISTN.STNID FROM InvoicePurchaseOrder IPO  (NOLOCK)
      LEFT JOIN InvoiceSTN ISTN  (NOLOCK) ON IPO.InvoiceID=ISTN.InvoiceID  WHERE SRPO.PurchaseOrderID=IPO.PurchaseOrderID
      UNION ALL
      SELECT SPO.PurchaseOrderID,SPO.STNID FROM STNPurchaseOrder(NOLOCK) SPO WHERE SPO.PurchaseOrderID=SRPO.PurchaseOrderID
   )  STPP  --ON SRPO.PurchaseOrderID=stpp.PurchaseOrderID

我已将其替换为

I REPLACED IT IN PLACE OF

LEFT JOIN 
  (
      SELECT IPO.PurchaseOrderID,ISTN.STNID FROM InvoicePurchaseOrder IPO  (NOLOCK)
      LEFT JOIN InvoiceSTN ISTN  (NOLOCK) ON IPO.InvoiceID=ISTN.InvoiceID  WHERE SRPO.PurchaseOrderID=IPO.PurchaseOrderID
      UNION ALL
      SELECT SPO.PurchaseOrderID,SPO.STNID FROM STNPurchaseOrder(NOLOCK) SPO 
   )  STPP  ON SRPO.PurchaseOrderID=stpp.PurchaseOrderID

请帮助我!!!



谢谢

SHREENIWAS

推荐答案

没有太多的信息，但请查看以下链接

http://www.mssqltips.com/sqlservertip/1958/sql-server-cross-apply-and-outer-apply / [ ^ ]

http ：//technet.microsoft.com/en-us/library/ms175156（v = sql.105）.aspx [ ^ ]

Don''t have much infromation but check below links
http://www.mssqltips.com/sqlservertip/1958/sql-server-cross-apply-and-outer-apply/[^]
http://technet.microsoft.com/en-us/library/ms175156(v=sql.105).aspx[^]

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