Question

考虑一下：

SELECT(count(c.id),
    case when(count(c.id) = 0)
             then 'loser'
         when(count(c.id) BETWEEN 1 AND 4)
             then 'almostaloser'
         when(count(c.id) >= 5)
             then 'notaloser'
    end as status,
   ...

当完成所有操作后，整个查询会生成一组看起来类似于此的结果：

   Count  | status
  --------|-------------
     2    | almostaloser   //total count is between 2 and 4
  --------|-------------
     0    | loser          // loser because total count = 0
  --------|-------------
     3    | almostaloser  //again, total count between 2 and 4
  --------|-------------

我想要实现的目标：

从上表中重新获取信息的方法，但添加第三列将给出每个状态的总计数，例如

   select count(c.id)
     case when(count(c.id) = 0 )
        then loser as status AND count how many  of the total count does this apply to

结果看起来类似于：

   Count  | status      |total_of each status |
  --------|-------------|---------------------|
     2    | almostaloser|   2                 |   
  --------|-------------|---------------------|
     0    | loser       |   1                 |  
  --------|-------------|---------------------|
     3    | almostaloser|   2                 |
  --------|-------------|----------------------

我被告知这可以使用派生表来实现，但我还没有能够得到它们，只有一个或另一个。

Answer 1

这可以通过此查询实现（您必须将原始查询作为子查询放在两个位置）：

SELECT t1.*, t2.total_of_each_status
  FROM (
    -- put here your query --
  ) t1
  INNER JOIN (
    SELECT status, count(*) AS total_of_each_status
      FROM (
        -- put here your query --
      ) t2
      GROUP BY status
  ) t2 ON t2.status = t1.status

Mysql计数用case语句时

1 个答案: