CREATE TABLE status (station_id VARCHAR, bikes_available VARCHAR)
CREATE TABLE station (name VARCHAR, id VARCHAR)

Return the unique name for stations that have ever had 7 bikes available.
SELECT DISTINCT T1.name FROM station AS T1 JOIN status AS T2 ON T1.id = T2.station_id WHERE T2.bikes_available = 7
SELECT DISTINCT "T1"."name" FROM "station" AS "T1" JOIN "status" AS "T2" ON "T1"."id" = "T2"."station_id" AND "T2"."bikes_available" = 7