【ocp-12c】最新Oracle OCP-071考试题库(37题)
19.choose the best answer
View the Exhibit and examine the structure of the PROMOTIONS table. Evaluate the following SQL statement: SQL>SELECT promo_name,CASE WHEN promo_cost>=(SELECT AVG(promo_cost) FROM promotions WHERE promo_category= ‘TV‘) THEN ‘HIGH‘ ELSE ‘LOW‘ END COST_REMARK FROM promotions; Which statement is true regarding the outcome of the above query? A) It shows COST_REMARK for all the promos in the promo category ‘TV‘ . B) It produces an error because subqueries cannot be used with the CASE expression. C) It shows COST_REMARK for all the promos in the table. D) It produces an error because the subquery gives an error. Answer:C (解析:category ‘TV‘只是判定 promo_cost 的一个条件,显示的是所有 category 的内容。 使用如下语句验证: SELECT promo_name,promo_category,CASE WHEN promo_cost>=(SELECT AVG(promo_cost) FROM promotions WHERE promo_category= ‘TV‘) THEN ‘HIGH‘ ELSE ‘LOW‘ END COST_REMARK FROM promotions where rownum < 30; ) (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |