在cakephp中调用函数

但每当调用此函数时，都会出现如下错误：-

public function data()
{ 
if($old != $status || $prev_lat != $lat || $prev_long != $long)
            {
                if($status == 'Village' || 'Unknown')
                {
                    exec_query();
                }
                else if($status == 'Town' || 'City')
                {
                    exec_query();
                }   
            }
}


public function exec_query()
{
    //Some data;
}

---

有人能告诉我hw在cakephp中调用函数吗？在函数名之前添加

$this->

，如下所示：

Call to undefined function exec_query() 

public function data()
{ 
if($old != $status || $prev_lat != $lat || $prev_long != $long)
            {
                if($status == 'Village' || 'Unknown')
                {
                    $this->exec_query();
                }
                else if($status == 'Town' || 'City')
                {
                    $this->exec_query();
                }   
            }
}


public function exec_query()
{
    //Some data;
}