假设我有一个带有数字列的表(让我们称之为“score”)。

我想生成一个计数表,显示分数在每个范围内出现的次数。

例如:

score range  | number of occurrences
-------------------------------------
   0-9       |        11
  10-19      |        14
  20-29      |         3
   ...       |       ...

在这个示例中,有11行分数在0到9之间,14行分数在10到19之间,3行分数在20到29之间。

有什么简单的方法吗?你有什么建议吗?


当前回答

也许你问的是如何让这样的事情继续下去……

当然,您将为查询调用全表扫描,如果包含需要统计(聚合)的分数的表很大,您可能想要一个性能更好的解决方案,您可以创建一个辅助表并使用规则,例如关于插入—您可能会研究它。

不过,并不是所有的RDBMS引擎都有规则!

其他回答

select t.range as score, count(*) as Count 
from (
      select UserId,
         case when isnull(score ,0) >= 0 and isnull(score ,0)< 5 then '0-5'
                when isnull(score ,0) >= 5 and isnull(score ,0)< 10 then '5-10'
                when isnull(score ,0) >= 10 and isnull(score ,0)< 15 then '10-15'
                when isnull(score ,0) >= 15 and isnull(score ,0)< 20 then '15-20'               
         else ' 20+' end as range
         ,case when isnull(score ,0) >= 0 and isnull(score ,0)< 5 then 1
                when isnull(score ,0) >= 5 and isnull(score ,0)< 10 then 2
                when isnull(score ,0) >= 10 and isnull(score ,0)< 15 then 3
                when isnull(score ,0) >= 15 and isnull(score ,0)< 20 then 4             
         else 5  end as pd
     from score table
     ) t

group by t.range,pd order by pd

也许你问的是如何让这样的事情继续下去……

当然,您将为查询调用全表扫描,如果包含需要统计(聚合)的分数的表很大,您可能想要一个性能更好的解决方案,您可以创建一个辅助表并使用规则,例如关于插入—您可能会研究它。

不过,并不是所有的RDBMS引擎都有规则!

select cast(score/10 as varchar) + '-' + cast(score/10+9 as varchar), 
       count(*)
from scores
group by score/10
select t.blah as [score range], count(*) as [number of occurences]
from (
  select case 
    when score between  0 and  9 then ' 0-9 '
    when score between 10 and 19 then '10-19'
    when score between 20 and 29 then '20-29'
    ...
    else '90-99' end as blah
  from scores) t
group by t.blah

如果在MySQL中,请确保使用'range'以外的单词,否则在运行上述示例时会出现错误。

在SQL Server 2000上,投票最多的答案都不正确。也许他们用的是另一个版本。

下面是在SQL Server 2000上这两个软件的正确版本。

select t.range as [score range], count(*) as [number of occurences]
from (
  select case  
    when score between 0 and 9 then ' 0- 9'
    when score between 10 and 19 then '10-19'
    else '20-99' end as range
  from scores) t
group by t.range

or

select t.range as [score range], count(*) as [number of occurrences]
from (
      select user_id,
         case when score >= 0 and score< 10 then '0-9'
         when score >= 10 and score< 20 then '10-19'
         else '20-99' end as range
     from scores) t
group by t.range