从titles表获取按照title进行分组

从titles表获取按照title进行分组，每组个数大于等于2，给出title以及对应的数目t。
CREATE TABLE IF NOT EXISTS "titles" (
emp_no int(11) NOT NULL,
title varchar(50) NOT NULL,
from_date date NOT NULL,
to_date date DEFAULT NULL);

思路：采用Group by+Having

select title,count(emp_no) as t from titles 
group by title having t>=2;