What are the phones and emails of workshop groups in which services are performed?
create table services (workshop_group_id varchar, PRIMARY KEY (workshop_group_id)); create table drama_workshop_groups (store_phone varchar, store_email_address varchar, workshop_group_id varchar, PRIMARY KEY (store_phone))
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