计算男性、女性和总数 [英] Count male, female and total

问题描述

我想从学生表中计算指定特定年份的男性、女性和学生总数.我希望结果是否可以以表格形式显示:

I want to count male, female and total students from Student table for a specific year specified. I wish if the result could be displayed in the form:

====================================
| Label    |  Value   |   Year     |
====================================
| Male     |   0      |   2013     |
| Female   |  23      |   2013     |
| Total    |  23      |   2013     |
====================================

如果指定年份没有男/女匹配，则查询应显示 0.知道我怎样才能做到这一点吗?

The query should display 0 if there is no male/female matching for the specified year. Any idea how I can make this happen?

提前致谢

推荐答案

考虑以下查询:

select
  max(registeredYear) as year,
  count(case when gender='Male' then 1 end) as male_cnt,
  count(case when gender='Female' then 1 end) as female_cnt,
  count(*) as total_cnt
from student
where registeredYear = 2013
group by registeredYear;

结果是这样的:

Year male_cnt female_cnt total_cnt
---- -------- ---------- ---------
2013        0         23        23

您可以将此结果转换为您想要的形式.如果您想在查询中执行此操作，则可以这样做:

You can transform this result into the form you want. If you want to do it within a query, then you can do it like this:

with t as (
    select
      max(registeredYear) as year,
      count(case when gender='Male' then 1 end) as male_cnt,
      count(case when gender='Female' then 1 end) as female_cnt,
      count(*) as total_cnt
    from student
    where registeredYear = 2013
    group by registeredYear)
select 'Male', male_cnt as male, year from t
union all
select 'Female', female_cnt as male, year from t
union all
select 'Total', total_cnt as male, year from t
;

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