mysql like 非模糊查询

当起始不是模糊查询时，其实是可以用索引的

explain extended select * from users where email like '303578599%'

explain extended select * from users where email like '303W8599%'

如果起始就是模糊查询，就要全表扫描了

explain extended select * from users where email like '03578599%'