PHP and MySQL Select a Single Value [duplicate]

Answer 1

try this

session_start();
$name = $_GET["username"];
$sql = "SELECT 'id' FROM Users WHERE username='$name' LIMIT 1 ";
$result = mysql_query($sql) or die(mysql_error());
if($row = mysql_fetch_assoc($result))
{
      $_SESSION['myid'] = $row['id'];
}

Answer 2

When you use mysql_fetch_object, you get an object (of class stdClass) with all fields for the row inside of it.

Use mysql_fetch_field instead of mysql_fetch_object, that will give you the first field of the result set (id in your case). The docs are here