Database: yelp
Question: Find the users who have given tips on Pet Groomers
SQL:
SELECT t4.name FROM category AS t2 JOIN business AS t1 ON t2.business_id  =  t1.business_id JOIN tip AS t3 ON t3.business_id  =  t1.business_id JOIN USER AS t4 ON t4.user_id  =  t3.user_id WHERE t2.category_name  =  "Pet Groomers";