Hi!
I have a page built in php for different projects within culture and arts.
In one part of the page the members of the page can presentate their projects.
In this part I would like to have a userlist with the possibility to check which other
members you have collaborated with in different projects like in the picture below.

The problem is when I check several checkboxes there will still just show up one collaboration on the page.
Heres an more detailed explanation:
I get the this userlist with the code:
// FROM
$projectmenu_selcatNY = '';
if ($sql->db_Select('user', 'user_id, user_name', ' GROUP BY user_id', 'nowhere', false))
{
while ($projectmenu_row = $sql->db_Fetch())
{
extract($projectmenu_row);
$projectmenu_selcatNY .= "$user_name<input type='checkbox' name='project_body' value='$user_name $user_id'<br ";
if ($user_id == $projectmenu_projectcat)
{
}
$projectmenu_selcatNY .= '>' . $tp->toFORM($projectmenu_bortmedborjan2[2], false) . '</option>';
}
}
$projectmenu_selcatNY .= '</select>';
// TO
2) And this results in a page like below with lists of the collaborations that are checked in the list:

With the code:
SC_BEGIN project_VIEW_BODY
global $tp,$user_id_project,$project_body,$user_id_project,$project_author,$projectmenu_postername,$user,$user_name,$projectmenu_postername;
return "<a href='".e_BASE."user.php?id.$project_body'>$project_body</a>";
SC_END
Where project_VIEW_BODY is a shortcode for a templatefile. And $project_body is the value from the checkbox.
Heres is also a picture of the database:

MY QUESTION:
The problem is when I check several checkboxes there will still just show up one collaboration on the page.
What shall I change in the code to be able to make several users to get registrated in the database?
So if I for example check:
It ends up with a database that looks like:
project_body:
Katapult, per3
Thanks a lot for help!!!
Perik