PHP didn't show text from table MySQL for specific user

Question

i tried to make some changes for my page. So,i want to show for users a specific coins what are in the table.(Table are created) But,when i try to doing this didn't work(didn't show) if i want for the username. Work only without verification for user id/name.

My code:

    $strSQL = "SELECT * FROM users WHERE id=" . $_GET["id"];
    $rs = mysql_query($strSQL);

    while($row = mysql_fetch_array($rs)) {

        echo "<dt>Coins:</dt><dd>" . $row["coins"] . "</dd>";

    }

I tried to $_GET["id"] with ["username"] .But also didn't work (Verification for session is like this: if(isset($_SESSION['username']))

Somebody know why didn't work?

Answer 1

$strSQL = "SELECT * FROM users WHERE id='".$_GET['id']."'";