CREATE TABLE table_37235 ("Round" FLOAT, "Date" CLOB, "Grand Prix" CLOB, "Circuit" CLOB, "125cc winner" CLOB, "250cc winner" CLOB, "MotoGP winner" CLOB, "Report" CLOB)

Which Date has a MotoGP winner of casey stoner, and a 250cc winner of hiroshi aoyama?
SELECT "Date" FROM table_37235 WHERE "MotoGP winner" = 'casey stoner' AND "250cc winner" = 'hiroshi aoyama'
SELECT "Date" FROM "table_37235" WHERE "250cc winner" = 'hiroshi aoyama' AND "MotoGP winner" = 'casey stoner'