Which is the email of the party that has used the services the most number of times?
CREATE TABLE parties (party_email VARCHAR, party_id VARCHAR); CREATE TABLE party_services (customer_id VARCHAR)
[SQL] SELECT t1.party_email FROM parties AS t1 JOIN party_services AS t2 ON t1.party_id = t2.customer_id GROUP BY t1.party_email ORDER BY COUNT(*) DESC LIMIT 1 [/SQL]