题解 | #考试分数(四)#

1.第一遍写的时候整太麻烦了，先是子查询取了job和count，然后再在子查询的基础上通过if判断奇偶数并分别求中位数，并用cast把小数转成整数。这里还踩了个大坑，cast没有int这个datatype，这里int是signed或者unsigned。太麻烦太麻烦了

select temp.job, 
if(temp.cnt % 2 <> 0, CAST((temp.cnt+1)/2 as UNSIGNED), CAST(temp.cnt/2 as UNSIGNED)) as start, 
if(temp.cnt % 2 <> 0, CAST((temp.cnt+1)/2 as UNSIGNED), CAST(temp.cnt/2+1 as UNSIGNED)) as end
from (select job, count(id) as cnt from grade
group by job) as temp
order by temp.job

2.这也太简单了！！！ceil=ceiling是向上取整，floor=flooring是向下取整

select job, floor((count(id)+1)/2), ceil((count(id)+1)/2) from grade
group by job
order by job