变量值与多个用户冲突

Iam new to PHP, trying to do personalized search engine it works fine with the single user... but simultaneously 2 user uses.. the values in the Variable showing wrong values.
Eg:
if user1 search "Apple" then $qry="Apple",
same time user2 search "orange" then $qry="orange"
that time the user1 will get the remaining stuffs related "orange".

function storewords($str,$id)
{
    $words= str_word_count($str,1);
    $cntstr = count($words);
    //echo $cntstr; 
    for($i=0;$i<$cntstr;$i++)
    {
        $allwords= $words[$i];
        $insert = "INSERT INTO freq (word,extra) VALUES ('".$allwords."','".$id."')";
        $add_member = mysql_query($insert);
    }
}

Which i have process of preprocessing, extracting concept for each user's content.. each user have different content. I think i have expressed my doubt in correct word, if no please excuse. Please help me, Thanks in advance

You just have to store user id somehow, to get separate "searches" for each user later.

$insert = "INSERT INTO freq (userid,word,extra) VALUES (...)";

Then you should select from that table using SELECT with filter like this: "WHERE userid=$current_user_id"