高频 SQL 50 题（基础版）_626. 换座位

select
    (case 
        when mod(id,2)!=0 AND counts != id then id+1
        when mod(id,2)!=0 AND counts = id then id
        else id -1
    end) as id,
    student
from
    seat,
    (select
    count(*) as counts
    from seat) as seat_counts
order by id asc;