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?
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
在我看来,James Curran的回答是最简洁的,但输出并不正确。对于SQL Server,最简单的语句如下:
SELECT
[score range] = CAST((Score/10)*10 AS VARCHAR) + ' - ' + CAST((Score/10)*10+9 AS VARCHAR),
[number of occurrences] = COUNT(*)
FROM #Scores
GROUP BY Score/10
ORDER BY Score/10
这假设了一个我用来测试它的#Scores临时表,我只是用0到99之间的随机数填充了100行。
其他回答
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。
declare @RangeWidth int
set @RangeWidth = 10
select
Floor(Score/@RangeWidth) as LowerBound,
Floor(Score/@RangeWidth)+@RangeWidth as UpperBound,
Count(*)
From
ScoreTable
group by
Floor(Score/@RangeWidth)
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 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
Try
SELECT (str(range) + "-" + str(range + 9) ) AS [Score range], COUNT(score) AS [number of occurances]
FROM (SELECT score, int(score / 10 ) * 10 AS range FROM scoredata )
GROUP BY range;