Database: yelp
Question: What is the number of restaurant in Pittsburgh rated 4.5
SQL:
SELECT COUNT ( DISTINCT t1.name ) FROM category AS t2 JOIN business AS t1 ON t2.business_id  =  t1.business_id WHERE t1.city  =  "Pittsburgh" AND t1.rating  =  4.5 AND t2.category_name  =  "restaurant";