用codeigniter也有一段時間了，一直沒有做什么總結。昨日亂逛，看到有同學總結了一下ci的數據庫操作，雖說不全，但是也確實可以幫助那些剛剛上手CI的同學。

鏈接數據庫
-------
$this->load->database();//手動連接數據庫
//連接多數據庫
$DB1 = $this->load->database('group_one', TRUE);
$DB2 = $this->load->database('group_two', TRUE);
-----------------------------------------------------

查詢
-------
//參數綁定形式
$sql = "SELECT * FROM some_table WHERE id = ? AND status = ? AND author = ?";
$this->db->query($sql, array(3, 'live', 'Rick'));
 
//多結果標準查詢
$query = $this->db->query($sql); //自定義
$query = $this->db->get('tablename'); //便捷形式，相當于:SELECT * FROM tablename
$query = $this->db->get('tablename', 10, 20); // 相當于: SELECT * FROM tablename LIMIT 20, 10
 
$query->result() //對象形式
$query->result_array() //數組形式
/*
foreach ($query->result() as $row)
{
    echo $row->title;
    echo $row->name;
    echo $row->email;
}
*/
$query->num_rows() //總條數
$query->num_fields() //字段數
 
//單結果標準查詢
$row = $query->row(); //對象形式
$row = $query->row_array(); //數組形式
/*
$row = $query->row_array();
echo $row['name'];
*/
 

插入
-------
$data = array(
                'title' => $title,
                'name' => $name
                );
$this->db->insert('tablename', $data); //便捷插入
$this->db->insert_string('tablename', $data);  //便捷插入
 
$this->db->insert_id() //剛插入的id
$this->db->affected_rows() //影響的行數(update,insert)
 

更新
-------
$data = array(
                'name' => $name,
                'email' => $email
                );
$where = "id = 1";
$this->db->update('tablename', $data);
$this->db->update_string('tablename', $data, $where);

刪除
-------
$array = array(
                'name' => $name,
                'title' => $title
                );
$this->db->delete('tablename', $array);
 
// Produces:
// "DELETE FROM tablename WHERE name = '$name' AND title = "$title""
 
$this->db->truncate('tablename'); //清空表
// Produce: TRUNCATE tablename
 
 
 
-----------------------------------------------------
（where）
-------
 
$array = array(
                'name' => $name,
                'title' => $title
                );
$this->db->where($array);
// Produces: "WHERE name = '$name' AND title = "$title""
-----------------------------------------------------
$this->db->count_all('tablename'); //表中記錄總行數
-----------------------------------------------------
$query->free_result() //釋放資源