Question

I was wondering if someone could help me
I have two tables 1) profile 2) mailbox_conversation
Each table has a common column called profile_id

I would like to find all the members in the profile table who have a membership_id = 107 (i.e. get a subset of members who have membership type 107 and they will be listed in an array by profile_id)
Then using that subset of members, find all the conversations in the table mailbox_conversation that have a profile_id in the subset – thus many emails may have the same profile_id and I would like them all deleted

Answer 1

Find emails which correspond to profiles with membership_id = 107

select m.id
from mailbox_conversation m
join profile p on p.profile_id = m.profile_id
                  and p.membership_id = 107

Delete those records

delete from mailbox_conversation
using mailbox_conversation, profile
where profile.profile_id = mailbox_conversation.profile_id
      and profile.membership_id = 107;

SQL Fiddle for playing around.