Table schema:
CREATE TABLE institution (institution_id VARCHAR, building_id VARCHAR); CREATE TABLE building (building_id VARCHAR, floors VARCHAR); CREATE TABLE protein (institution_id VARCHAR)

Question: How many proteins are associated with an institution in a building with at least 20 floors?
SQL: SELECT COUNT(*) FROM institution AS T1 JOIN protein AS T2 ON T1.institution_id = T2.institution_id JOIN building AS T3 ON T3.building_id = T1.building_id WHERE T3.floors >= 20