Question

我有3张桌子

products [which contains data related to products]
    productid (int)
    name (varchar)
    price (float)

sales [which contains data related to sales]
    salesid (int)
    productid (int)
    time (datetime)

links [which contains data related to links from products]
    linkid (int)
    productid (int)
    link (text)

我需要输出

ProductID   Name   TotalSales    TotalLinkAvailable
    1       ABCD       10               12
    1       EFGH       7                25

如何使用单个查询实现此目的？

由于

修改

我尝试了以下不起作用的查询：

select p.name,count(s.salesid) as Sales, count(l.linkid) as Links 
from products p 
left join sales s on p.productid=s.productid 
left join links l on p.products=l.productid 
group by p.productid

Answer 1

select p.productid, p.name, count(s.salesid) as TotalSales, count(l.linkid) as TotalLinkAvailable
    from products p
        left join sales s
            on p.productid = s.productid
        left join links l
            on p.productid = l.productid
    group by p.productid, p.name

Answer 2

select p.pname,count(s.salesid) as Sales ,count(l.linkid) as Links
 from products p left join sales s on p.productid=s.productid
 left join links l on p.products=l.productid 
group by p.productid

Answer 3

SELECT p.productid AS ProductID, p.name AS Name, COUNT(s.salesid) AS TotalSales, COUNT(l.linkid) AS TotalLinkAvailable
FROM products AS p
LEFT JOIN sales AS s ON s.productid = p.productid
LEFT JOIN links AS l ON l.productid = p.productid
GROUP BY p.productid, p.name

假设在示例性查询结果的第二行中有关于ProductID的拼写错误。

3表计数查询mysql

3 个答案: