Question

要求：

原始表：SCORE

+--------+----------+-----------+
| Math   | English  | Chemistry |
+--------+----------+-----------+
| 69     | 82       | 95        |
+--------+----------+-----------+

类别： - [0-80] - ＆gt; C - [80-90] - ＆gt;乙 - [90-100] - ＆gt; A

输出应为

+--------+----------+-----------+
| Math   | English  | Chemistry |
+--------+----------+-----------+
| C      | B        |    A      |
+--------+----------+-----------+

我应该在Oracle中测试，但现在我首先在MySQL上进行测试。我的代码如下：

CREATE table grade1(
Math varchar(10),
English varchar(10),
Chemistry varchar(10))

INSERT INTO grade1 (Math, English, Chemistry)
VALUES (

SELECT
CASE
when Math < 80 then 'C'
when Math > 80 and Math <90 then 'B'
when Math > 90 and Math <100 then 'A'
END
FROM SCORE,

SELECT
CASE
when English < 80 then 'C'
when English > 80 and English < 90 then 'B'
when English > 90 and English < 100 then 'A'
END
FROM SCORE,

SELECT
CASE
when Chemistry < 80 then 'C'
when Chemistry > 80 and Chemistry <90 then 'B'
when Chemistry > 90 and Chemistry <100 then 'A'
END  
FROM SCORE)

请检查是否有任何错误？因为我无法运行它。

Answer 1

这个怎么样？

INSERT INTO grade1 (Math, English, Chemistry)
    VALUES (
        SELECT
            CASE
                WHEN Math >= 90 then 'A'
                WHEN Math >= 80 then 'B'
                WHEN Math < 80 then 'C'
            END Math,
            CASE
                WHEN English >= 90 then 'A'
                WHEN English >= 80 then 'B'
                WHEN English < 80 then 'C'
            END English,
            CASE
                WHEN Chemistry >= 90 then 'A'
                WHEN Chemistry >= 80 then 'B'
                WHEN Chemistry < 80 then 'C'
            END Chemistry
        FROM SCORE)

您不必在每个CASE之前使用SELECT。我改变了WHEN值的顺序。

我可以在MySQL中使用多个案例吗？

1 个答案: