Oracle多条件count

select
    count(case when field1='A' then 1 end)数量1,
    count(case when field2='B' then 1 end)数量2,
    count(case when field3='C' then 1 end)数量3,
    count(case when field4='D' then 1 end)数量4,
    count(case when  1=1 then 1 end)总数4
from test;