Question

我需要查询才能获得每个级别的参与者数量。

注意：4级参与者不应该处于其他级别（3,2,1级）。即我只对每个参与者的最高级别感兴趣。

表：

  +----+-------+----------+
  | ID | Level |  Date    |
  +----+-------+----------+
  | 38 | 1     |  06 -05  |
  | 38 | 2     |  08 -05  |
  | 38 | 3     |  12 -05  |
  | 38 | 4     |  13 -05  |
  | 39 | 1     |  13 -05  |
  | 39 | 2     |  13 -05  |
  | 40 | 1     |  12 -05  |
  +----+-------+----------+

需要输出：

  +-------+-------+ 
  | Count | Level | 
  +-------+-------+ 
  | 1     | 1     |
  | 1     | 2     |
  | 0     | 3     |
  | 1     | 4     |
  +-------+-------+

Answer 1

试试这个：

SELECT count(t2.Id) as count,t1.Level as level
FROM table1 t1
LEFT JOIN
(SELECT Id,MAX(Level) as Level
FROM table1
GROUP BY Id ) t2 on t1.Id=t2.Id and t1.Level=t2.Level
GROUP BY t1.Level

您可以在SQL Fiddle

上进行测试

Answer 2

我认为你正在寻找

Select Count(*), Level FROM table_name GROUP BY Level

Answer 3

预期结果是知道有多少人将级别作为最高级别，按级别进行分组。

SELECT count(id) as count, level
FROM
(
  SELECT id, max(level) as level
  FROM myTable
  GROUP BY id
) t1
GROUP BY level;

Sql Query使用表检索数据

3 个答案: