626.md

-- 看github 圖，基本上就是交叉2個2個做，到最後再問odd？

select
    if(id < (select max(id) from seat),
        if(id%2=0, id-1, id+1),  
        if(id%2=0, id-1, id)
    ) as id,
    student
from seat
order by id