sql在使用join时删除重复记录

Question

我有一个无法更改的下表结构。

我正在尝试加入这些表，并希望避免重复记录。

 select p.ProductId,p.ProductName,inv.Details from Products p
inner join Inventory inv on(p.ProductId = inv.ProductId)

这里是SqlFiddle。

Answer 1

从sqlserver 2008+开始，您可以使用交叉申请。

使用交叉应用，您可以在子选择内部进行连接，如此处所示。使用前1名，您可以从表库存中获得最多1行。也可以通过＆＃39;添加＆＃39;顺序。对子选择的陈述。但是，这似乎超出了您的问题的范围。

select p.ProductId,p.ProductName,x.Details 
from Products p
cross apply
(SELECT top 1 inv.Details FROM Inventory inv WHERE p.ProductId = inv.ProductId) x

Answer 2

您可以使用row_number函数删除重复项

   WITH New_Inventory AS
    (
        SELECT Productid, Details,
        ROW_NUMBER() OVER (Partition by Productid ORDER BY details) AS RowNumber
        FROM Products
    ) 
    select p.ProductId,p.ProductName,inv.Details from Products p
    inner join New_Inventory inv on(p.ProductId = inv.ProductId)
    where RowNumber = 1

Answer 3

select p.ProductId,p.ProductName 
,(select top 1 inv.Details from  Inventory inv where (p.ProductId = inv.ProductId))Details
from Products p

或

select * from 
(
select p.ProductId,p.ProductName,inv.Details
,ROW_NUMBER()over(partition by p.productid order by p.productid)rn from Products p
inner join Inventory inv on(p.ProductId = inv.ProductId)
)t4 
where rn=1

Answer 4

with cte as 
(select p.ProductId,p.ProductName,inv.Details,
RoW_Number() OVER(Partition by  p.ProductId,p.ProductName,inv.Details
                  Order by p.ProductId,p.ProductName,inv.Details) rn
 from Products p
inner join Inventory inv on(p.ProductId = inv.ProductId))

select ProductId,ProductName,Details from cte where rn = 1

SQLFIDDLE