SQL Join-同一张表中的两个外键引用一个主键

Question

我有两个表，一个是产品转换历史记录表，另一个是产品表：

dbo.Product_Change_History

Date  FK_ProductID FK_FinalProductID ChangedBy
20160709    1               3           John

dbo.Product_Detail

PK_ProductID ProductName 
     1        Red Bike
     3        Green Bike

我想要一张像这样的桌子：

 Date      ProductName FinalProductName
20160709   Red Bike     Green Bike

我如何结合两个表来实现这一目标？ 编辑：这是在TSQL中

Answer 1

您必须加入两次，这意味着您至少要为其中一个加入别名：

SELECT Date, foo.ProductName, bar.FinalProductName
FROM Product_Change_history
LEFT JOIN Product_Detail AS foo ON fk_productid = foo.pk_productid
LEFT JOIN Product_Detail AS bar ON fk_finalproductid = bar.pk_productid

Answer 2

我不确定LEFT是否加入VS INNER。 我认为这会很好。

SELECT
 link.Date,
 old.ProductName,
 new.ProductName as FinalProductName
FROM
 dbo.Product_Detail as old
 INNER JOIN dbo.Product_Change_History as link
  ON old.PK_ProductID = link.FK_ProductID
 INNER JOIN dbo.Product_Detail as new
  ON new.PK_ProductID = link.FK_FinalProductID

Answer 3

declare @ProdChange table(ProductID int, FK_ProductID INT, FK_FinalProductID INT, ChangedBy Varchar(100))

declare @Prod table(ProductID int, ProductName Varchar(100))

insert into @Prod Values(1,'Red Bike')
insert into @Prod Values(3,'Green Bike')

insert into @ProdChange Values(1,1,3,'John')
select * from @Prod
select * from @ProdChange

SELECT 
 old.ProductName,
 new.ProductName as FinalProductName
FROM
 @Prod as old
 INNER JOIN @ProdChange as link
  ON old.ProductID = link.FK_ProductID
 INNER JOIN @Prod as new
  ON new.ProductID = link.FK_FinalProductID

Answer 4

感谢您的答复，在Chad Zinks的帮助下，我找到了正确的解决方案：

select
PRDHIST.Date,
OLDPROD.ProductName,
NEWPROD.ProductName
from dbo.Product_ChangeHistory PRDHIST
inner join dbo.Product_Detail OLDPROD
on OLDPROD.PK_ProductID = PRDHIST.FK_ProductID
inner join dbo.Product_Detail NEWPROD
on NEWPROD.PK_ProductID = PRDHIST.FK_FinalProductID;