如果存在现有记录，则单选按钮未预填充

这是一个简单的应用程序，表单包含3个问题。每个问题有2个选项。如果用户以前提交过答案，那么表单应该预先填充，但由于某种原因，它没有。

这是代码。非常感谢任何帮助或指导。

<?php
    $user_id = $_SESSION['user_id'];
    $anthem1 = '';
    $cointoss2 = '';
    $firstscore3 = ''; 
    if (isset($_POST['submit'])) {
        if (isset($_POST['anthem1'])) {
            $anthem1 = mysqli_real_escape_string($connection, $_POST['anthem1']);
        }       
        if (isset($_POST['cointoss2'])) {
             $cointoss2 = mysqli_real_escape_string($connection, $_POST['cointoss2']);
        }       
        if (isset($_POST['firstscore3'])) {
             $firstscore3 = mysqli_real_escape_string($connection, $_POST['firstscore3']);
        }

        $query = "INSERT INTO mypicks (user_id, anthem1, cointoss2, firstscore3) 
                      VALUES ('{$user_id}','{$anthem1}','{$cointoss2}','{$firstscore3}')
                      ON DUPLICATE KEY UPDATE anthem1 = '{$anthem1}',
                      cointoss2 = '{$cointoss2}',
                      firstscore3 = '{$firstscore3}'";

        $result = mysqli_query($connection, $query);
    }

    $query = "SELECT * FROM mypicks WHERE user_id = {$user_id}";
    $result = mysqli_query($connection, $query);
    if($result->num_rows == 1) {
        $user_picks = mysqli_fetch_row($result);
        $anthem1 = $user_picks['anthem1'];
        $cointoss2 = $user_picks['cointoss2'];
        $firstscore3 = $user_picks['firstscore3'];
    }
?>

这是表格（其中一个问题）：

<form action="Game1_MyPicks.php" method="post">
Will the National Anthem be over 3 mins and 15 secs? <br />
Over  <input type="radio" name="anthem1" value="Over" <?php if ($anthem1=="Over") print('checked="checked"') ?>/><br />
Under <input type="radio" name="anthem1" value="Under" <?php if ($anthem1=="Under") print('checked="checked"') ?>/><br />
</form>