SQL 统计一个列中的三种值的数量，并在一个表中显示

select sum(case when status='child' then 1 else 0 end) as 'child 数量' ,sum(case when status='young' then 1 else 0 end) as 'young 数量' ,sum(case when status='old' then 1 else 0 end) as 'old 数量'from