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
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
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;
因为要排序的列(Range)是一个字符串,所以使用字符串/单词排序而不是数值排序。
只要字符串有0来填充数字长度,排序在语义上仍然是正确的:
SELECT t.range AS ScoreRange,
COUNT(*) AS NumberOfOccurrences
FROM (SELECT CASE
WHEN score BETWEEN 0 AND 9 THEN '00-09'
WHEN score BETWEEN 10 AND 19 THEN '10-19'
ELSE '20-99'
END AS Range
FROM Scores) t
GROUP BY t.Range
如果范围是混合的,简单地填充一个额外的0:
SELECT t.range AS ScoreRange,
COUNT(*) AS NumberOfOccurrences
FROM (SELECT CASE
WHEN score BETWEEN 0 AND 9 THEN '000-009'
WHEN score BETWEEN 10 AND 19 THEN '010-019'
WHEN score BETWEEN 20 AND 99 THEN '020-099'
ELSE '100-999'
END AS Range
FROM Scores) t
GROUP BY t.Range
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!
在postgres中(其中||是字符串连接操作符):
select (score/10)*10 || '-' || (score/10)*10+9 as scorerange, count(*)
from scores
group by score/10
order by 1
给:
scorerange | count
------------+-------
0-9 | 11
10-19 | 14
20-29 | 3
30-39 | 2
下面是如何在T-SQL中做到这一点:
DECLARE @traunch INT = 1000;
SELECT
CONCAT
(
FORMAT((score / @traunch) * @traunch, '###,000,000')
, ' - ' ,
FORMAT((score / @traunch) * @traunch + @traunch - 1, '###,000,000')
) as [Range]
, FORMAT(MIN(score), 'N0') as [Min]
, FORMAT(AVG(score), 'N0') as [Avg]
, FORMAT(MAX(score), 'N0') as [Max]
, FORMAT(COUNT(score), 'N0') as [Count]
, FORMAT(SUM(score), 'N0') as [Sum]
FROM scores
GROUP BY score / @traunch
ORDER BY score / @traunch
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