vyplňte zaškrtávací políčka a poté aktualizujte výběr na mysql

Neměli byste mít stejné ID více než jednou na stránce.

A uzavřete atribut value pomocí '

<?php
   foreach ($values as $value) {
   $selected = in_array($value, $db_values) ? ' checked="checked"' : null;
   echo "<input type='checkbox' name='sports[]' id ='sport' value='" . $value ."' " . $selected . "/>" . $value . "<br />";
} ?>

Vytvořte pole takto

$arr['F'] = "Football";
$arr['R'] = "Rugby";
$arr['C'] = "Cricket";

$arr[$value] instead of $value

UPRAVIT

<?php
    $arr['F'] = "Football";
    $arr['R'] = "Rugby";
    $arr['C'] = "Cricket";
    foreach ($values as $value) {
        $selected = in_array($value, $db_values) ? ' checked="checked"' : null;
        echo "<input type='checkbox' name='sports[]' id ='sport' value=" . $value . $selected . "/>" . $arr[$value] . "<br />";
    }
?>