like 模糊查询 ci框架

$this->db->like('title', 'match', 'before'); 
// 生成: WHERE title LIKE '%match' 

$this->db->like('title', 'match', 'after'); 
// 生成: WHERE title LIKE 'match%' 

$this->db->like('title', 'match', 'both'); 
// 生成: WHERE title LIKE '%match%'