I am building a social network, and I need a simple internal search engine that will display a list of all website users starting with the ones that have the specific keyword in their username. So here is what i need:

a search engine that will take a keyword. the search engine will open a new page with a list of all website users, displaying first the users that have the specific keyword in their username. display your username in the placeholder. So, here is what I have so far:

<div class="logobox r">
  <form method="post" action="../sity/search.php"> <!--will redirect you to a new page with a list of all website users.-->
    <input type="text" class="logo" name="searchUser" placeholder="<?php echo $comObj->getSession('username')?>"> <!--will take a keyword as a imput, and will display your username in the placeholder-->
    <button type="submit" class="sity" value="sity">sity</button>
  </form>
</div>

And here is the searchUser function:

function searchUser($keyword) {

  $commObj = new common;

  $sql = "SELECT `id`,`username`, `profile_pic`  FROM  ".$this->tables['user']."  WHERE `username` LIKE '%".$keyword."%' AND `id` <> ".$commObj->getSession('userid');

  $result = $this->selectAll($sql);

  unset($this->rsa);          
  return $result; 
}

The problem is that when you click on the search box, instead of letting you to enter a keyword, the page will logout you from the website. I still can't figure out why.

Here is the link to the website: www.sity.net

Any suggestion will be highly appreciated.

Thanks