Question

只是了解UNION查询 - 节省时间 - 但是在分组方面遇到了麻烦。

我有以下声明：

(SELECT `shops`.shpUserAdded AS userName, count(`shops`.shpID) AS shpCount, "" AS prdCount FROM `shops` GROUP BY shpUserAdded ASC)
UNION
(SELECT `products`.prdUserAdded AS userName, "" AS shpCount, count(`products`.prdID) AS prdCount FROM `products` GROUP BY prdUserAdded ASC)

但是这给了我第一个查询的结果，然后是第二个查询的结果，没有组合用户名：

userName|merCount|prdCount 
        |       8|
Jane    |       1|
Derek   |       1|
James   |      22|
        |        |       3
Jane    |        |       4  
Derek   |        |       5
James   |        |      21

我尝试过（但显然得到了#1248 - Every derived table must have its own alias）：

SELECT userName, shpCount, prdCount FROM
((SELECT `shops`.shpUserAdded AS userName, count(`shops`.shpID) AS shpCount, "" AS prdCount FROM `shops` GROUP BY shpUserAdded ASC)
UNION
(SELECT `products`.prdUserAdded AS userName, "" AS shpCount, count(`products`.prdID) AS prdCount FROM `products` GROUP BY prdUserAdded ASC))
GROUP BY userName ASC

我似乎无法在不擦除shpCount或prdCount列中的数据的情况下找出派生表的命名 - 任何建议？我可能会感到愚蠢，但是在那里！

解决了（真的这次）！：）

SELECT Users.userName, Products.prdCount, Shops.shpCount FROM 
(
    (
        (SELECT `Shops`.shpAddU AS userName FROM `Shops` GROUP BY shpAddU ASC)
        UNION
        (SELECT `Products`.prdAddU AS userName FROM `Products` GROUP BY prdAddU ASC)
    ) AS Users
) 
LEFT JOIN 
(SELECT prdAddU AS userName, count(*) AS prdCount FROM `Products` GROUP BY prdAddU) as Products ON Users.userName = Products.userName
LEFT JOIN 
(SELECT shpAddU AS userName, count(*) AS shpCount FROM `Shops` GROUP BY shpAddU) as Shops ON Users.userName = Shops.userName

Answer 1

并非所有东西都是联盟 - 在这种情况下，它是子查询的连接：

SELECT shpUserAdded AS userName, merCount, prdCount
FROM (SELECT shpUserAdded, count(*) AS shpCount FROM shops GROUP BY shpUserAdded ASC) AS s
JOIN (SELECT prdUserAdded, count(*) AS prdCount FROM products GROUP BY prdUserAdded ASC) AS p
ON (shpUserAdded = prdUserAdded);

MySQL Union查询重复/分组问题

1 个答案: