What are all the workshop groups?
select * from drama_workshop_groups
What about those that services are performed?
select * from drama_workshop_groups as t1 join services as t2 on t1.workshop_group_id = t2.workshop_group_id
Show their phones and emails.
select t1.store_phone, t1.store_email_address from drama_workshop_groups as t1 join services as t2 on t1.workshop_group_id = t2.workshop_group_id