How many businesses in Phoenix, Arizona is attributed to waiter service?
'Phoenix' is the city; waiter service refers to attribute_name = 'waiter_services'
SELECT COUNT(T1.business_id) FROM Business AS T1 INNER JOIN Business_attributes AS T2 ON T1.business_id = T2.business_id INNER JOIN Attributes AS T3 ON T2.attribute_id = T3.attribute_id WHERE T1.city LIKE 'Phoenix' AND T3.attribute_name LIKE 'waiter_service' AND T2.attribute_id = 2