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  • 【ocp12c】最新Oracle OCP071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;

    )

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  • 原文地址:https://www.cnblogs.com/cnblogs5359/p/10437588.html
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