Question

id | userid | total_points_spent
1  | 1      | 10
2  | 2      | 15
3  | 2      | 50
4  | 3      | 5
5  | 1      | 15

根据上表，我首先要删除userid的重复项，保留最大total_points_spent的行，如下所示：

id | userid | total_points_spent
3  | 2      | 50
4  | 3      | 5
5  | 1      | 15

然后我想总结total_points_spent的值，这将是最简单的部分，从而产生70。

Answer 1

我不确定“删除”是指删除或选择。以下是分别仅选择max totalpointspend记录的查询。

SELECT tblA.* 
  FROM ( SELECT userid, MAX(totalpointspend) AS maxtotal
           FROM tblA
           GROUP BY userid ) AS dt
INNER JOIN tblA 
    ON tblA.userid = dt.userid
   AND tblA.totalpointspend = dt.maxtotal           
ORDER BY tblA.userid

从一列中删除重复项，保留整行

1 个答案: