获得表中的最大记录

Question

我有这样的表：

表学校

ID_School     name
--------------------
ACH001        jack
ACH001        gon
ACH001        fanny
ACH001        tony
ACH002        vera
ACH002        jessica
ACH003        rey
ACH003        tomy

我希望输出此表中的最大记录ID_School，输出如下：

ID_School  count
-----------------
ACH001     4

Answer 1

就是这样：

select ID_school,count(ID_school) as total from school group by names order by total desc limit 1;

Answer 2

在MS SQL中：

select top 1 ID_School, count(*) IdCount
from school
group by ID_School
order by IdCount desc

Answer 3

对于Oracle：

SELECT id_school, cnt
  FROM (SELECT id_school, count(*) cnt
          FROM school
         GROUP BY id_school
         ORDER BY cnt)
 WHERE ROWNUM = 1;