次のSQLステートメントを評価します SQL> SELECT promo_id、prom _categoryFROMプロモーション WHERE promo_category = 'Internet' ORDER BY promo_id 連合 SELECT promo_id、promo_category FROM Pomotions WHERE promo_category = 'TV' 連合 SELECT promoid、promocategory FROM Promotions WHERE promo category = 'Radio' 上記のクエリの結果に関して正しい説明はどれですか?
正解:C
* C. It executes successfully but ignores the ORDER BY clause because it is not located at the end of the compound statement: The ORDER BY clause in a compound query using UNION should be placed at the very end of the final SELECT statement. Since it's located with the first SELECT, it will be ignored.