表中数据如上如所示， 要求查询出来的结果是： 
第一步，查询出title相等的name
SELECT * FROM ceshi GROUP BY name HAVING count(DISTINCT(title)) =1
其中函数DISTINCT是去重复函数，按name分组并且去完重复的title只有一条的说明该name所拥有的title都相同 第二步，查出name的所有数据
方法1：
SELECT *FROM ceshi where name in(SELECT `name` FROM ceshi GROUP BY name HAVING count(DISTINCT(title)) =1 );
方法2：
SELECT A.* from (SELECT * FROM ceshi GROUP BY name HAVING count(DISTINCT(title)) =1) as A LEFT JOIN ceshi AS B on A.name=B.name;