mysql - 如何找出特定月份最常用的已售图书类别

Question

我正在尝试计算特定月份(例如一月)销售最多副本(书籍)的类别。我的 payment_date 列采用日期时间格式。它说我的 SQL 语法中存在以下查询的错误

SELECT category_id, SUM(payment_amount) AS Total FROM Payments GROUP BY category_id WHERE MONTH(payment_date) = 01 ORDER BY SUM(payment_amount) DESC LIMIT 1

Answer 1

语句的 GROUP BY 部分需要位于 WHERE 子句之后，因此您的查询应该是:

SELECT category_id, SUM(payment_amount) AS Total FROM Payments WHERE MONTH(payment_date) = 1 GROUP BY category_id ORDER BY SUM(payment_amount) DESC LIMIT 1