with temp as (
    select
        author_id
    from
        answer_tb a left join issue_tb i on a.issue_id = i.issue_id
    group by
        author_id
    having
        sum(if(issue_type='Education',1,0)) > 0 and sum(if(issue_type='Career',1,0)) > 0
)

select
    count(*) as num
from
    temp