SQL查询:对于每个值,确定包含该值的行的百分比?

如果您真的想知道确切人数所占的百分比,请使用:

SELECT
    NoteCount,
    COUNT(*) ContactsWithThisNoteCount,
    COUNT(*) / (SELECT COUNT(*) FROM Contacts) PercentageContactsWithThisNoteCount
FROM 
    Contacts
GROUP BY
    NoteCount

select 
((countTen/countTotal)*100) as percentTen,
((countHundred/countTotal)*100) as percentHundred
FROM (
  select 
  cast(sum(case when noteCount <= 10 then 1 else 0 end) as float) as countTen,
  cast(sum(case when noteCount <= 100 and > 10 then 1 else 0 end) as float) as countHundred,
  cast(count(*) as float) as countTotal
  from
  contacts
) temp

应该没问题,我经常使用技巧和+情况时,我需要做一个过滤器计数