php递归函数没有返回任何值

Question

I write this recursive function but its not working. Not able to find the mistake. Its not returning anything. But If I write an "echo" on else statement its printing perfectly.

function find_parent($referralid,$leg)
{   
    $query="SELECT memberid FROM memberdetails where parentid='".$referralid."'  and leg='".$leg."'";
    $result=mysql_query($query);
    if (mysql_num_rows($result) == 0) 
        return $referralid;
    else
    {
        while($row = mysql_fetch_array($result))
        {
            find_parent($row[0],$leg);
        }
    }   
}

Answer 1

When you have recursion, you need to pass the value back as well, otherwise the value isn't propagated back up. So the line which is...

find_parent($row[0],$leg);

needs to be

return find_parent($row[0],$leg);

This is assuming that you will only ever get 1 row as a parent.