题解 | #统计所有课程参加培训人次#

with t as(
select 
    staff_id,
    if(course like '%1%',1,0) as course1,
    if(course like '%2%',1,0) as course2,
    if(course like '%3%',1,0) as course3
from cultivate_tb
where course is not null)

select sum(course1)+sum(course2)+sum(course3) as staff_nums
from t