MySQL查询问题

Question

我有4个表

Table: Category 
    CategoryID (int) 
    Name (varchar) 
Table: Products 
    ProductID (int) 
    CategoryID (int) 
    Name (varchar) 
    Description (text) 
Table: Sales 
    SalesID (int) 
    ProductID (int) 
Table: Links 
    LinkID (int) 
    ProductID (int) 

现在我需要显示的数据为：我怎样才能做到这一点

CategoryName  Total Products  Total Sales  Total Links 
    ABC    5     12   50 
    XYZ    12     26   10 

，可在单个查询

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谢谢

Answer 1

SELECT c.Name AS "CategoryName", COUNT(p.ProductID) AS "TotalProducts", COUNT(s.SalesID) AS "TotalSales", COUNT(l.LinkID) AS "TotalLinks" 
FROM Category c 
INNER JOIN Products p ON p.CategoryID = c.CategoryID 
INNER JOIN Sales s ON s.ProductID = p.ProductID 
INNER JOIN Links l ON l.ProductID = s.ProductID; 

我不知道如何将数据看起来像，但你可能需要添加一个GROUP BY的地方，如果你有重复或可选ORDER BY如果需要排序在任何列