CREATE TABLE claims (claim_id DECIMAL, policy_id DECIMAL, date_claim_made TIME, date_claim_settled TIME, amount_claimed DECIMAL, amount_settled DECIMAL)
CREATE TABLE payments (payment_id DECIMAL, settlement_id DECIMAL, payment_method_code TEXT, date_payment_made TIME, amount_payment DECIMAL)
CREATE TABLE settlements (settlement_id DECIMAL, claim_id DECIMAL, date_claim_made TIME, date_claim_settled TIME, amount_claimed DECIMAL, amount_settled DECIMAL, customer_policy_id DECIMAL)
CREATE TABLE customers (customer_id DECIMAL, customer_details TEXT)
CREATE TABLE customer_policies (policy_id DECIMAL, customer_id DECIMAL, policy_type_code TEXT, start_date TIME, end_date TIME)

Which payment method is used the most often?
SELECT payment_method_code FROM payments GROUP BY payment_method_code ORDER BY COUNT(*) DESC LIMIT 1
SELECT "payment_method_code" FROM "payments" GROUP BY "payment_method_code" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1