CRUD应用程序错误编号1054

我得到这个错误有人知道是什么可能是这个原因吗?我想是模型出了问题，但我不明白。

错误编号:1054

order子句中未知列'id'

SELECT * FROM ( tblquestions ) ORDER BY id asc LIMIT 5

文件名:C: ' wamp ' www数据库'苏尔'系统' ' DB_driver.php

行号:330

private $primary_key = 'QID';
private $table_name = 'tblquestions';
function get_paged_list($limit=10, $offset=0, $order_column='', $order_type='asc')
{
    if (empty($order_column) || empty($order_type)) {
        $this->db->order_by($this->primary_key, 'asc'); 
    }
    else {
        $this->db->order_by($order_column, $order_type);
        return $this->db->get($this->table_name, $limit, $offset);
    }
}
function count_all()
{
    return $this->db->count_all($this->table_name); 
}
function get_by_id($id)
{
    $this->db->where($this->primary_key, $id);
    return $this->db->get($this->table_name);
}
function save($question)
{
    $this->db->insert($this->table_name, $question);
    return $this->db->insert_id();  
}
function update($id,$question)
{
    $this->db->where($this->primary_key, $id);  
    $this->db->update($this->table_name, $question);
}
function delete($id)
{
    $this->db->where($this->primary_key, $id);
    $this->db->delete($this->table_name);
}