avoid duplicated friend

[tuananh87vn]

hi,
I'mm writing script for adding friend to a friend list.i'm using a form including friend_name (text), message (textarea) and below is my code:
[php]
if(isset($_POST['send']))
{

include('dbconnect.php');

$friend=$_POST['friend2'];
$user=$_COOKIE['username'];


$result=mysql_query("SELECT * FROM friendlist WHERE username='$user'");
$rows=mysql_fetch_array($result);
echo $friend;
$added_friend=$rows['friend'];
echo $added_friend;
$user1=$rows['username'];
echo $user1;

if(($friend==$added_friend)&&($user==$user1))
{
?><script>alert('<? echo $friend; ?> has been on your list already!');
window.location="friendpublic.php";
</script><?
}

else
{
$query="INSERT INTO friendlist (username,friend) VALUES ('$user','$friend')";
mysql_query($query) or die(mysql_error);

?><script>alert('<? echo $friend; ?> has been added to your list!')</script><?

$invite=$_POST['invite'];
$query2="INSERT INTO friend_message (sender,receiver,message,status)
VALUES ('$user','$friend','$invite','1')";
mysql_query($query2) or die(mysql_error);

?><script>alert('A message has been sent to him or her!');
window.location="friendpublic.php";
</script><?

}

}

?>
[/php]

the code [php]if(($friend==$added_friend)&&($user==$user1))[/php] is used to check if the friend was already on the list but somehow it doesn't work. i think the problem is the mysql_fetch_assoc which queries the first row on the friendlist table...

can anyone show me how to fix it?

thanks!

[code green]

You are making hard work of it.
If all you want to do is check if the current applicant is already in the database then change this [PHP]$friend=$_POST['friend2'];
$user=$_COOKIE['username'];


$result=mysql_query("SELECT * FROM friendlist WHERE username='$user'");
$rows=mysql_fetch_array($result);
echo $friend;
$added_friend=$rows['friend'];
echo $added_friend;
$user1=$rows['username'];
echo $user1;

if(($friend==$added_friend)&&($user==$user1))
{
?><script>alert('<? echo $friend; ?> has been on your list already!');[/PHP] To [PHP]
$friend=$_POST['friend2'];
$user=$_COOKIE['username'];
$result=mysql_query("SELECT 1 FROM friendlist WHERE `username`='$user'");
if(mysql_num_rows($result)
?><script>alert('<? echo $friend; ?> has been on your list already!');[/PHP]
Is $user reliable? If it is simply a name typed in a text box it is not.
I assume you are collecting emails so test the email address.
You could also set the field in friendlist to UNIQUE then capture any errors when INSERTing

[tuananh87vn]

it doesnot work! I could only add the first friend into my list. for all of these other. the message says they've been added already.

[code green]

it doesnot work! I could only add the first friend into my list. for all of these other. the message says they've been added already

Please don't use the meaningless

it doesnot work

What others are you talking about?
Can I suggest you break the problem down into smaller steps then we can find where it is going wrong.

[tuananh87vn]

Please don't use the meaningless What others are you talking about?
Can I suggest you break the problem down into smaller steps then we can find where it is going wrong.

oh sorry, I'd have made it clearer!
when I use my first code:
[php]
$result=mysql_query("SELECT * FROM friendlist WHERE username='$user'");
$rows=mysql_fetch_array($result);
$added_friend=$rows['friend'];
$user1=$rows['username'];

if(($friend==$added_friend)&&($user==$user1))
{
warning of duplication
}

else
{ ...}
[/php]

I tried to take all of my friend names from my list and compared each of them to one I'm going to add. The problem is the query seems to take only the first name in the table and keep it for any later comparison (say if I add A first then B, C... only later adding A receives warning of duplication, B, C.. do not)

(using while loop for my_fetch_array shouldn't be mentioned: multiple adding for each name^^)

in the second code given by you,
[php]
$result=mysql_query("SELECT 1 FROM friendlist WHERE `username`='$user'");
if(mysql_num_rows($result)
{ warning}
[/php]
things seem even worse: only first friend name added, all others receives warning....

can you help me? thanks!

[code green]

By this

I tried to take all of my friend names from my list

I assume you mean the `friendlist` table. If so write `friendlist` table and not 'my list'.
Programmers should be precise in their explanation.

and compared each of them to one I'm going to add

There is never a wrong way but you are coming close.
I would stop and have a re-think. You seem to be tackling this the wrong way around.
Are you bulk uploading a list of new friends or only one?
If it is a bulk upload, first load them all into an array,
then loop through the array and query each one seperately
with the `friendlist` table to see if they are there with the query I gave you.
Then you can handle the result however you like for each list item.
If there is only then use the query I gave you.
DO NOT SELECT * FROM `friendlist`, then loop through the entire result set looking for a match.
This is madness.