Question

我有以下查询：

SELECT * FROM quotes 
INNER JOIN quotes_panels ON quotes.wp_user_id = quotes_panels.ID 
WHERE quotes.created >= '$startDate' 
AND quotes.created <= '$endDate' AND quotes.wp_user_id != '0'

此查询可以从同一个用户生成多行（quotes.wp_user_id），但我只想显示具有最大屋顶区域的行（quotes.roofarea）。

但是，当我添加GROUP BY quotes.wp_user_id时，它会自动采用最低的quotes.ID行而不是具有最大quotes.roofarea的行。将ORDER BY quotes.roofarea DESC添加到查询的末尾时，它会对整个结果进行排序，而不仅仅是“GROUP BY”的结果。

有人可以协助获得查询所需的结果吗？

由于

Answer 1

您必须先对行进行排序。

SELECT * FROM (SELECT * FROM quotes 
INNER JOIN quotes_panels ON quotes.wp_user_id = quotes_panels.ID 
WHERE quotes.created >= '$startDate' 
AND quotes.created <= '$endDate' AND quotes.wp_user_id != '0' 
ORDER BY quotes.roofarea DESC) a 
GROUP BY a.wp_user_id

Answer 2

在MySQL中GROUP BY在ORDER BY之前完成，因此您需要在两个查询中执行此操作：

SELECT * FROM
    (SELECT * FROM quotes 
    INNER JOIN quotes_panels ON quotes.wp_user_id = quotes_panels.ID 
    WHERE quotes.created >= '$startDate' 
    AND quotes.created <= '$endDate' AND quotes.wp_user_id != '0'
    ORDER BY quotes.roofarea DESC) AS subset
GROUP BY subset.wp_user_id

Answer 3

您必须添加如下聚合函数：

SELECT *, MAX(quotes.roofarea) FROM quotes 
INNER JOIN quotes_panels ON quotes.wp_user_id = quotes_panels.ID 
WHERE quotes.created >= '$startDate' 
AND quotes.created <= '$endDate' AND quotes.wp_user_id != '0'
GROUP BY quotes.wp_user_id

在这里阅读更多相关信息：

http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html

Answer 4

试试这个

SELECT * FROM quotes 
INNER JOIN quotes_panels ON quotes.wp_user_id = quotes_panels.ID 
WHERE quotes.created >= '$startDate' 
AND quotes.created <= '$endDate' AND quotes.wp_user_id != '0'
AND quotes.roofarea = (SELECT MAX(q.roofarea) FROM quotes q WHERE q.wp_user_id = quotes.wp_user_id)
GROUP BY quotes.wp_user_id

立即检查

在MySQL中进行组排序

4 个答案: