方法一：使用 like 筛选

select
s.staff_id,s.staff_name
from staff_tb s inner join cultivate_tb c on s.staff_id = c.staff_id
where course is not null and course like '%course3%'
order by s.staff_id

方法二：使用find_in_set()

select
s.staff_id,s.staff_name
from staff_tb s inner join cultivate_tb c on s.staff_id = c.staff_id
where find_in_set('course3',course)>0
order by s.staff_id