mysql - 如果多个用户具有相同的计数值，则分配相同的排名

Question

我有包含两列的 user_points 表。

根据用户 ID 的计数，从 user_points 中选择 user_values、userid 我想将排名分配给用户..我已经写了这个查询

SELECT count_temp.* ,  @curRank:=(@curRank + 1) AS rank
 FROM (
    SELECT userid, COUNT(*) AS totalcount FROM user_points t GROUP BY t.userid
 ) AS count_temp 
, (SELECT @curRank := 0) r 
ORDER BY totalcount DESC;

给出的结果为:

---

用户名 |总数 |排名

---

2        6      1
3        2      2
4        2      3
1        1      4

但我想为 userid 3 和 4 assgin 排名 2，因为它们的总数相同..

Answer 1

要模拟 RANK() 函数，该函数返回结果集分区内每一行的排名，您可以这样做

SELECT userid, totalcount, rank
  FROM
(
  SELECT userid, totalcount, 
         @n := @n + 1, @r := IF(@c = totalcount, @r, @n) rank, @c := totalcount 
    FROM 
  (
    SELECT userid, COUNT(*) AS totalcount 
      FROM user_points t 
     GROUP BY t.userid
     ORDER BY totalcount DESC
  ) t CROSS JOIN 
  (
    SELECT @r := 0, @n := 0, @c := NULL
  ) i
) q;

输出:

| USERID | TOTALCOUNT | RANK |
|--------|------------|------|
|      2 |          6 |    1 |
|      3 |          2 |    2 |
|      4 |          2 |    2 |
|      1 |          1 |    4 |

To emulate DENSE_RANK() function, which returns the rank of rows within the partition of a result set, without any gaps in the ranking, you can do

SELECT userid, totalcount, rank
  FROM
(

  SELECT userid, totalcount, 
         @r := IF(@c = totalcount, @r, @r + 1) rank, @c := totalcount
    FROM 
  (
    SELECT userid, COUNT(*) AS totalcount 
      FROM user_points t 
     GROUP BY t.userid
     ORDER BY totalcount DESC
  ) t CROSS JOIN 
  (
    SELECT @r := 0, @c := NULL
  ) i
) q;

输出:

| USERID | TOTALCOUNT | RANK |
|--------|------------|------|
|      2 |          6 |    1 |
|      3 |          2 |    2 |
|      4 |          2 |    2 |
|      1 |          1 |    3 |

这是 SQLFiddle 两个查询的演示