mysql查询返回整体排名

Question

我有一个包含以下数据的用户表：

+----+------------+--------------+--------------+--------------+
| id | name       | points_game1 | points_game2 | points_game3 |
+----+------------+--------------+--------------+--------------+
|  1 | player 1   |           10 |            0 |            5 |
|  2 | player 2   |            0 |           25 |            0 |
|  3 | player 3   |           30 |            3 |            0 |
|  4 | player 4   |            0 |            0 |           20 |
+----+------------+--------------+--------------+--------------+

我希望能够显示整体排名，其中排名被定义为总体最高分而不是每场比赛的排名。因此，在上面的示例中，我将使用什么查询来显示此结果：

+----+------------+-------+----------------+
| id | name       | score | game           |
+----+------------+-------+----------------+
|  3 | player 3   |    30 | points_game1   |
|  2 | player 2   |    25 | points_game2   |
|  4 | player 4   |    20 | points_game3   |
|  1 | player 1   |    10 | points_game1   |
+----+------------+-------+----------------+

Answer 1

以下查询回答了您的问题：

SELECT 
  id, 
  name, 
  GREATEST(points_game1, points_game2, points_game3) AS score,
  CASE
    WHEN points_game1 = GREATEST(points_game1, points_game2, points_game3) THEN 'points_game1'
    WHEN points_game2 = GREATEST(points_game1, points_game2, points_game3) THEN 'points_game2'
    WHEN points_game3 = GREATEST(points_game1, points_game2, points_game3) THEN 'points_game3'
  END AS game
FROM
  users
ORDER BY 
  3 DESC

由于GREATEST（...）计算的重复性而有点粗糙。您可能希望将其放在子查询中。

在任何情况下，请注意此查询不会使用表上的任何索引，因为ORDER BY使用了一个函数而不是列 - 这会消除MySQL中密钥的使用。