CREATE TABLE table_6252 ("Year" FLOAT, "Class" TEXT, "Team" TEXT, "Chassis" TEXT, "Tyre" TEXT, "Laps" FLOAT)

Which Class has a Chassis of Mazda 787B?
SELECT "Class" FROM table_6252 WHERE "Chassis" = 'mazda 787b'
SELECT "Class" FROM "table_6252" WHERE "Chassis" = 'mazda 787b'