CREATE TABLE table_69664 ("Round" FLOAT, "Date" TEXT, "Grand Prix" TEXT, "Circuit" TEXT, "125cc winner" TEXT, "250cc winner" TEXT, "MotoGP winner" TEXT, "Report" TEXT)

Name the date for motogp winner of casey stoner and grand prix of valencian grand prix
SELECT "Date" FROM table_69664 WHERE "MotoGP winner" = 'casey stoner' AND "Grand Prix" = 'valencian grand prix'
SELECT "Date" FROM "table_69664" WHERE "Grand Prix" = 'valencian grand prix' AND "MotoGP winner" = 'casey stoner'