Compute the most commonly used payment types
select CASE
WHEN payment_type=1 THEN 'Credit Card'
WHEN payment_type=2 THEN 'Cash'
WHEN payment_type=3 THEN 'No charge'
WHEN payment_type=4 THEN 'Dispute'
WHEN payment_type=5 THEN 'Unknown'
WHEN payment_type=6 THEN 'Voided Trip'
ELSE 'N/A'
END AS payment_type, count(*)
from nyctaxis
group by payment_type
order by count(*) DESC
limit 10