Find the emails of parties with the most popular party form.
create table party_forms (form_id varchar, PRIMARY KEY (form_id)); create table parties (party_email varchar, party_id varchar, PRIMARY KEY (party_email)); create table party_forms (party_id varchar, form_id varchar, PRIMARY KEY (party_id))
select t1.party_email from parties as t1 join party_forms as t2 on t1.party_id = t2.party_id where t2.form_id = (select form_id from party_forms group by form_id order by count(*) desc limit 1)