如何在不使用 AS 關鍵字的情況下重新表達此查詢？

Question

我正在完成 HackerRank 挑戰，但文件說我不應該使用 AS 關鍵字：

我需要在MySQL 中重寫此查詢，以便它不包含WITH A AS 中的AS，也不包含SELECT...AS test 中的AS

WITH A AS (
    SELECT DISTINCT
        MAX( LENGTH( customer_id ) ) AS test
    FROM
        orders

    UNION

    SELECT DISTINCT
        MIN( LENGTH( customer_id ) )
    FROM
        orders
)
SELECT
    test,
    LENGTH(test)
FROM
    A

Answer 1

WITH 子句用於宣告 VIEW，因此您可以像下面這樣重寫它

SELECT
    test,
    LENGTH(test)
FROM
    (
 SELECT DISTINCT
        MAX( LENGTH( customer_id ) ) AS test
    FROM
        orders

    UNION

    SELECT DISTINCT
        MIN( LENGTH( customer_id ) )
    FROM
        orders)