Question

我正在编写查询以从两个表Products，ProductsImages中获取数据。我的疑问是：

    SELECT p.*, pi.*
    FROM ( SELECT *, ROW_NUMBER() OVER (PARTITION BY ProductId, ProductPrice 
    ORDER BY ProductId) AS row_number FROM Products ) p
    INNER JOIN ( SELECT *, ROW_NUMBER() 
     OVER (PARTITION BY ProductId, ImageId,ImagePath  
    ORDER BY ImageId) AS row_number FROM ProductsImages ) pi 
    ON  p.ProductId = pi.ProductId
    AND p.row_number = pi.row_number
    Where p.ProductId='131';

我必须编写一个运行INNER JOIN的条件：如果ProductsImages具有提供productId 的图像，则实现INNER JOIN，否则它应该在没有连接的情况下运行。并且仅显示除图像之外的产品详细信息。如果productsImages没有任何图像，此查询不会显示产品详细信息，如名称和价格。
限制：我必须只实施INNER JOIN。 请帮助我并指导我如何在这种情况下实现if-exits条件。感谢名单

Answer 1

在这种情况下，你为什么不写left join,

左连接保留产品表中的所有记录，即使对于具有图像表的非匹配记录

也是如此

 SELECT p.*, pi.*
    FROM ( SELECT *, ROW_NUMBER() OVER (PARTITION BY ProductId, ProductPrice 
    ORDER BY ProductId) AS row_number FROM Products ) p
    LEFT OUTER JOIN ( SELECT *, ROW_NUMBER() 
     OVER (PARTITION BY ProductId, ImageId,ImagePath  
    ORDER BY ImageId) AS row_number FROM ProductsImages ) pi 
    ON  p.ProductId = pi.ProductId
    AND p.row_number = pi.row_number
    Where p.ProductId='131';

Answer 2

您可以尝试内部查询方式。例如：

SELECT p.*, ( SELECT *, ROW_NUMBER() 
OVER (PARTITION BY ProductId, ImageId,ImagePath  
ORDER BY ImageId) AS row_number FROM ProductsImages pi WHERE p.ProductId = pi.ProductId AND p.row_number = pi.row_number )
FROM ( SELECT *, ROW_NUMBER() OVER (PARTITION BY ProductId, ProductPrice 
ORDER BY ProductId) AS row_number FROM Products ) p
Where p.ProductId='131';

此处没有加入。：（

具有数据退出条件的INNER JOIN

2 个答案: