$query = $this->db->from('user')->where(array('username' => 'BobbyPeng'))->get();
return $query->row_array();

public function findByAttributes($where = array())
{
  $query = $this->db->from($this->tableName())->where($where)->get();
  return $query->row_array();
}

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
class ActiveRecord extends CI_Model
{
  /**
   * 保存數(shù)據(jù)
   * 
   * @param array $data 需要插入的表數(shù)據(jù)
   * @return boolean 插入成功返回ID，插入失敗返回false
   */
  public function save($data)
  {
    if($this->db->set($data)->insert($this->tableName())) {
      return $this->db->insert_id();
    }
    return FALSE;
  }
  /**
   * Replace數(shù)據(jù)
   * @param array $data
   */
  public function replace($data)
  {
    return $this->db->replace($this->tableName(), $data);
  }
  /**
   * 根據(jù)主鍵更新記錄
   * 
   * @param string $pk 主鍵值
   * @param array $attributes 更新字段
   * @param array $where 附加where條件
   * @return boolean true更新成功 false更新失敗
   */
  public function updateByPk($pk, $attributes, $where = array())
  {
    $where[$this->primaryKey()] = $pk;
    return $this->updateAll($attributes, $where);
  }
  /**
   * 更新表記錄
   * 
   * @param array $attributes
   * @param array $where
   * @return bollean true更新成功 false更新失敗
   */
  public function updateAll($attributes, $where = array())
  {
    return $this->db->where($where)->update($this->tableName(), $attributes);
  }
  /**
   * 根據(jù)主鍵刪除數(shù)據(jù)
   * 
   * @param string $pk 主鍵值
   * @param array $where 附加刪除條件
   * @return boolean true刪除成功 false刪除失敗 
   */
  public function deleteByPk($pk, $where = array())
  {
    $where[$this->primaryKey()] = $pk;
    return $this->deleteAll($where);
  }
  /**
   * 刪除記錄
   * 
   * @param array $where 刪除條件
   * @param int $limit 刪除行數(shù)
   * @return boolean true刪除成功 false刪除失敗
   */
  public function deleteAll($where = array(), $limit = NULL)
  {
    return $this->db->delete($this->tableName(), $where, $limit);
  }
  /**
   * 根據(jù)主鍵檢索
   * 
   * @param string $pk
   * @param array $where 附加查詢條件
   * @return array 返回一維數(shù)組，未找到記錄則返回空數(shù)組
   */
  public function findByPk($pk, $where = array())
  {
    $where[$this->primaryKey()] = $pk;
    $query = $this->db->from($this->tableName())->where($where)->get();
    return $query->row_array();
  }
  /**
   * 根據(jù)屬性獲取一行記錄
   * @param array $where
   * @return array 返回一維數(shù)組，未找到記錄則返回空數(shù)組
   */
  public function findByAttributes($where = array())
  {
    $query = $this->db->from($this->tableName())->where($where)->limit(1)->get();
    return $query->row_array();
  }
  /**
   * 查詢記錄
   * 
   * @param array $where 查詢條件，可使用模糊查詢，如array('name LIKE' => "pp%") array('stat >' => '1')
   * @param int $limit 返回記錄條數(shù)
   * @param int $offset 偏移量
   * @param string|array $sort 排序, 當(dāng)為數(shù)組的時候 如：array('id DESC', 'report_date ASC')可以通過第二個參數(shù)來控制是否escape
   * @return array 未找到記錄返回空數(shù)組
   */
  public function findAll($where = array(), $limit = 0, $offset = 0, $sort = NULL)
  {
    $this->db->from($this->tableName())->where($where);
    if($sort !== NULL) {
      if(is_array($sort)){
        foreach($sort as $value){
          $this->db->order_by($value, '', false);
        }
      } else {
        $this->db->order_by($sort);
      }
    }
    if($limit > 0) {
      $this->db->limit($limit, $offset);
    }
    $query = $this->db->get();
    return $query->result_array();
  }
  /**
   * 統(tǒng)計滿足條件的總數(shù)
   * 
   * @param array $where 統(tǒng)計條件
   * @return int 返回記錄條數(shù)
   */
  public function count($where = array())
  {
    return $this->db->from($this->tableName())->where($where)->count_all_results();
  }
  /**
   * 根據(jù)SQL查詢， 參數(shù)通過$param綁定
   * @param string $sql 查詢語句，如SELECT * FROM some_table WHERE id = ? AND status = ? AND author = ?
   * @param array $param array(3, 'live', 'Rick')
   * @return array 未找到記錄返回空數(shù)組，找到記錄返回二維數(shù)組
   */
  public function query($sql, $param = array())
  {
    $query = $this->db->query($sql, $param);
    return $query->result_array();
  }
}
/* End of file ActiveRecord.php */
/* Location: ./application/core/database/ActiveRecord.php */

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
require_once APPPATH.'core/database/ActiveRecord.php';
class MY_Model extends ActiveRecord 
{
  public function __construct($group_name = '')
  {
    $this->initDb($group_name);
    parent::__construct();
  }
  protected function initDb($group_name = '')
  {
    $db_conn_name = $this->getDbName($group_name);
    $CI = & get_instance();
    if(isset($CI->{$db_conn_name}) && is_object($CI->{$db_conn_name})) {
      $this->db = $CI->{$db_conn_name};
    } else {
      $CI->{$db_conn_name} = $this->db = $this->load->database($group_name, TRUE);
    }
  }
  private function getDbName($group_name = '')
  {
    if($group_name == '') {
      $db_conn_name = 'db';
    } else {
      $db_conn_name = 'db_'.$group_name;
    }
    return $db_conn_name;
  }
}
/* End of file MY_Model.php */
/* Location: ./application/core/MY_Model.php */