CREATE TABLE table_5610 ("School" TEXT, "Location" TEXT, "Mascot" TEXT, "County" TEXT, "Year Joined" FLOAT, "Previous Conference" TEXT, "Year Left" FLOAT, "Conference Joined" TEXT)

Which Conference Joined has a Previous Conference of northwestern, and a Mascot of oilers?
SELECT "Conference Joined" FROM table_5610 WHERE "Previous Conference" = 'northwestern' AND "Mascot" = 'oilers'
SELECT "Conference Joined" FROM "table_5610" WHERE "Mascot" = 'oilers' AND "Previous Conference" = 'northwestern'