数据库1000万条数据,统计

select count(*) as num from userinfo where name like '%班%'

下面是我测试的结果:

select count(*) as num  from lifi_a where name like "%班%"   //5.28   查询统计结果11336

select count(id) as num   from lifi_a where name like "%班%"  //5.64   查询统计结果11336

select count(*) as num from lifi_a where  name like '班%' //0秒  查询统计结果3739

select count(*) as num from lifi_a where  name like '%班'  //5.40秒   查询统计结果3828

有什么更好的方法优化吗?  我看like '班%'   加上索引以后是挺快  但是查询出来的结果就不对了