列 x 必须出现在 GROUP BY 子句中或在聚合函数中使用

Question

SELECT newTable.book_id
FROM (
    SELECT book_id, SUM(stock) AS stock
    FROM editions JOIN stock ON (editions.isbn = stock.isbn)
    GROUP BY book_id

    ) AS newTable
HAVING stock = max(stock);

我希望此代码生成 book_id 库存最多的图书，即库存图书的最大份数。我收到以下错误：

ERROR:  column "newtable.book_id" must appear in the GROUP BY clause or be used in an aggregate function
LINE 2:  SELECT newTable.book_id
                ^

********** Error **********

ERROR: column "newtable.book_id" must appear in the GROUP BY clause or be used in an aggregate function

有什么解决办法吗？

PS。已经尝试在末尾添加 GROUP BY newtable.book_id, newtable.stock 。它产生了语法错误。

谢谢！

Answer 1

我认为您可以考虑如下编写查询。您只需按要聚合的列进行排序，这样最多 "in stock" 将位于顶部，然后使用 LIMIT 子句从顶部删除 X 项。在这种情况下，LIMIT 1.

SELECT book_id, SUM(stock) AS numstock
FROM editions JOIN stock ON (editions.isbn = stock.isbn)
GROUP BY book_id
ORDER BY numstock desc
LIMIT 1

列 x 必须出现在 GROUP BY 子句中或在聚合函数中使用

Column x must appear in the GROUP BY clause or be used in an aggregate function

sql

postgresql

greatest-n-per-group