CREATE TABLE table_18303274_1 (grand_prix VARCHAR2, race_winner VARCHAR2)

What grand prixs did Daijiro Hiura win?
SELECT grand_prix FROM table_18303274_1 WHERE race_winner = "Daijiro Hiura"
SELECT "grand_prix" FROM "table_18303274_1" WHERE "Daijiro Hiura" = "race_winner"