题解 | #统计每种性别的人数#

# 先提取性别并作为性别标记列【注意不要用male来相似，因为female里面也具有male】
select *, case
when profile like '%female' then 'female'
else 'male'
end as gender
from user_submit
# 使用分组查询统计两种性别的参赛用户数目，【当使用子查询时一定要为其设置别名，不然会找不到这个表】
select gender, count(*) number
from (
    select *, case
    when profile like '%female' then 'female'
    else 'male'
    end as gender
    from user_submit
) gender_f
group by gender;