mysql - 选择列中具有最大值的行

Question

我正在尝试选择 numTimesPurchasedTable 中在 numTimesPurchased 列上具有最大值的行

SELECT item, title, MAX(numTimesPurchased) 
FROM (SELECT Purchase.item, Item.title, SUM(quantity) AS numTimesPurchased 
FROM Item INNER JOIN Purchase ON Item.id = Purchase.item 
GROUP BY item, title) AS numTimesPurchasedTable;

numTimesPurchasedTable 看起来像这样

item title numTimesPurchased
1    a     4
2    b     7
3    c     7

但是，我收到错误：“错误代码：1140。在没有 GROUP BY 的聚合查询中，SELECT 列表的表达式 #1 包含非聚合列 'numTimesPurchasedTable.item'”

有没有办法在一个查询中完成此操作？

标签： mysqldatabaseselectmax

Answer 1

如果您只需要具有最大值的单行，则使用 LIMIT：

SELECT Purchase.item, Item.title, SUM(quantity) AS numTimesPurchased 
FROM Item INNER JOIN Purchase ON Item.id = Purchase.item 
GROUP BY item, title
ORDER BY numTimesPurchased DESC LIMIT 1;