MySQL的case条件语句

626.换座位

代码来源（力扣评论）

SELECT (CASE 
            WHEN MOD(id,2) = 1 AND id = (SELECT COUNT(*) FROM seat) THEN id
            WHEN MOD(id,2) = 1 THEN id+1
            ElSE id-1
        END) AS id, student
FROM seat
ORDER BY id;

查询表seat记录的行数

SELECT COUNT(*) FROM seat

我自己的思路

select 
case
	when id % 2 =1 and id=(select max(id) as Max_id from seat ) then id
	when id % 2 =0 then id-1
	when id % 2 =1 then id+1 
end 
as id,student from seat 
order by id