comments | difficulty | edit_url | tags | |
---|---|---|---|---|
true |
中等 |
|
表: Seat
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| id | int |
| student | varchar |
+-------------+---------+
id
是该表的主键(唯一值)列。
该表的每一行都表示学生的姓名和 ID。
id 是一个连续的增量。
编写解决方案来交换每两个连续的学生的座位号。如果学生的数量是奇数,则最后一个学生的id不交换。
按 id
升序 返回结果表。
查询结果格式如下所示。
示例 1:
输入: Seat 表: +----+---------+ | id | student | +----+---------+ | 1 | Abbot | | 2 | Doris | | 3 | Emerson | | 4 | Green | | 5 | Jeames | +----+---------+ 输出: +----+---------+ | id | student | +----+---------+ | 1 | Doris | | 2 | Abbot | | 3 | Green | | 4 | Emerson | | 5 | Jeames | +----+---------+ 解释: 请注意,如果学生人数为奇数,则不需要更换最后一名学生的座位。
# Write your MySQL query statement below
SELECT s1.id, COALESCE(s2.student, s1.student) AS student
FROM
Seat AS s1
LEFT JOIN Seat AS s2 ON (s1.id + 1) ^ 1 - 1 = s2.id
ORDER BY 1;
# Write your MySQL query statement below
SELECT
id + (
CASE
WHEN id % 2 = 1
AND id != (SELECT MAX(id) FROM Seat) THEN 1
WHEN id % 2 = 0 THEN -1
ELSE 0
END
) AS id,
student
FROM Seat
ORDER BY 1;
# Write your MySQL query statement below
SELECT
RANK() OVER (ORDER BY (id - 1) ^ 1) AS id,
student
FROM Seat;
# Write your MySQL query statement below
SELECT
CASE
WHEN id & 1 = 0 THEN id - 1
WHEN ROW_NUMBER() OVER (ORDER BY id) != COUNT(id) OVER () THEN id + 1
ELSE id
END AS id,
student
FROM Seat
ORDER BY 1;