/**
* //查询表内的数据
* $res = $this->db->get(‘表名‘);
* $res->result();
* //添加数据
* $bool = $this->db->insert(‘表名‘,$data);
* //获取自增id
* $this->db->insert_id();
* //更新数据
* $bool = $this->db->update(‘表名‘,$data,array(‘id‘=>3));
* //删除数据
* $bool = $this->db->detele(‘表名‘,array(‘id‘=>2));
* //连贯操作
* $res = $this->db->select(‘id,name‘)
* ->from(‘表名‘)
* ->where(‘id>=‘,3)
* ->limit(2,3)
* ->order_by(‘iddesc‘)
* ->get();
* $list = $res->result();
* //显示最近一条sql
* echo $this->db->last_query();
* ci里面limit的顺序是相反的
*
* $res = $this->db->where(array(‘name‘=>‘mary‘,‘id‘=>2))->get(‘表名‘);
* //复杂查询
* $this->db->query($sql,$data);
*
*/
