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
另一种方法是将范围存储在表中,而不是将它们嵌入到查询中。你最终会得到一个表,命名为Ranges,它看起来像这样:
LowerLimit UpperLimit Range
0 9 '0-9'
10 19 '10-19'
20 29 '20-29'
30 39 '30-39'
查询如下所示:
Select
Range as [Score Range],
Count(*) as [Number of Occurences]
from
Ranges r inner join Scores s on s.Score between r.LowerLimit and r.UpperLimit
group by Range
这确实意味着要建立一个表,但是当所需的范围发生变化时,维护这个表是很容易的。不需要更改代码!
其他回答
我会用一种稍微不同的方式来做,这样它就不必定义每种情况:
select t.range as [score range], count(*) as [number of occurences]
from (
select FLOOR(score/10) as range
from scores) t
group by t.range
没有测试过,但你懂的…
create table scores (
user_id int,
score int
)
select t.range as [score range], count(*) as [number of occurences]
from (
select user_id,
case when score >= 0 and score < 10 then '0-9'
case when score >= 10 and score < 20 then '10-19'
...
else '90-99' as range
from scores) t
group by t.range
select cast(score/10 as varchar) + '-' + cast(score/10+9 as varchar),
count(*)
from scores
group by score/10
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
我在这里是因为我有类似的问题,但我发现简短的答案是错误的,一个连续的“情况下”是太多的工作,看到任何重复在我的代码伤害我的眼睛。这就是解
SELECT --MIN(score), MAX(score),
[score range] = CAST(ROUND(score-5,-1)AS VARCHAR) + ' - ' + CAST((ROUND(score-5,-1)+10)AS VARCHAR),
[number of occurrences] = COUNT(*)
FROM order
GROUP BY CAST(ROUND(score-5,-1)AS VARCHAR) + ' - ' + CAST((ROUND(score-5,-1)+10)AS VARCHAR)
ORDER BY MIN(score)