//查詢:
$query = $this->db_query("SELECT * FROM table");
 ==================================

//result() 返回對象數(shù)組
$data = $query->result();

//result_array() 返回數(shù)據(jù)
$data = $query->result_array();

//row() 只返回一行對象數(shù)組
$data = $query->row();

//num_rows() 返回查詢結(jié)果行數(shù)
$data = $query->num_rows();

//num_fields() 返回查詢請求的字段個數(shù)
$data = $query->num_fields();

//row_array() 只返回一行數(shù)組
$data = $query->row_array();

//free_result() 釋放當前查詢所占用的內(nèi)存并刪除關(guān)聯(lián)資源標識
$data = $query->free_result();

/*
 ==================================
 插入操作
 ==================================
*/

//上次插入操作生成的ID
echo $this->db->insert_id();

//寫入和更新操作被影響的行數(shù)
echo $this->db->affected_rows();

//返回指定表的總行數(shù)
echo $this->db->count_all('table_name');

//輸出當前的數(shù)據(jù)庫版本號
echo $this->db->version();

//輸出當前的數(shù)據(jù)庫平臺
echo $this->db->platform();

//返回最后運行的查詢語句
echo $this->db->last_query();

//插入數(shù)據(jù)，被插入的數(shù)據(jù)會被自動轉(zhuǎn)換和過濾，例如：
//$data = array('name' => $name, 'email' => $email, 'url' => $url);
$this->db->insert_string('table_name', $data);

/*
 ==================================
 更新操作
 ==================================
*/

//更新數(shù)據(jù)，被更新的數(shù)據(jù)會被自動轉(zhuǎn)換和過濾，例如：
//$data = array('name' => $name, 'email' => $email, 'url' => $url);
//$where = "author_id = 1 AND status = 'active'";
$this->db->update_string('table_name', $data, $where);

/*
 ==================================
 選擇數(shù)據(jù)
 ==================================
*/

//獲取表的全部數(shù)據(jù)
$this->db->get('table_name');

//第二個參數(shù)為輸出條數(shù)，第三個參數(shù)為開始位置
$this->db->get('table_name', 10, 20);

//獲取數(shù)據(jù)，第一個參數(shù)為表名，第二個為獲取條件，第三個為條數(shù)
$this->db->get_where('table_name', array('id'=>$id), $offset);

//select方式獲取數(shù)據(jù)
$this->db->select('title, content, date');
$data = $this->db->get('table_name');

//獲取字段的最大值，第二個參數(shù)為別名，相當于max(age) AS nianling
$this->db->select_max('age');
$this->db->select_max('age', 'nianling');

//獲取字段的最小值
$this->db->select_min('age');
$this->db->select_min('age', 'nianling');

//獲取字段的和
$this->db->select_sum('age');
$this->db->select_sum('age', 'nianling');

//自定義from表
$this->db->select('title', content, date');
$this->db->from('table_name');

//查詢條件 WHERE name = 'Joe' AND title = "boss" AND status = 'active'
$this->db->where('name', $name);
$this->db->where('title', $title);
$this->db->where('status', $status);

//范圍查詢
$this->db->where_in('item1', 'item2');
$this->db->where_not_in('item1', 'item2');

//匹配，第三個參數(shù)為匹配模式 title LIKE '%match%'
$this->db->like('title', 'match', 'before/after/both');