默认情况下，从字符串或数组值检查复选框

Question

我正在构建一个可以在事后编辑的提交表单，并且有一系列提交到数组的复选框，但是当我编辑数据时，我想要先检查先前选中的框。当表单最初提交时，复选框全部进入一个数组，该数组将被内置到数据库中的单个单元格中。这是我到目前为止所做的。

<?php
$query  = "SELECT * FROM profile WHERE username = '{$_SESSION['username']}' ";
$result = mysqli_query($connection, $query);
if (!$result) {
    $_SESSION["message"] = "You have not built your profile yet.";
    redirect_to("my_profile.php");
} 
$row = mysqli_fetch_array($result);
$activities   = $row['activities'];
?>  


<fieldset>  
     <legend>What kind of activities do you enjoy?</legend><br />
     <input type="checkbox" name="activities[]" value="sailing"/>Sailing
     <input type="checkbox" name="activities[]" value="hiking"/>Hiking
     <input type="checkbox" name="activities[]" value="gaming"/>Gaming<br />
     <input type="checkbox" name="activities[]" value="mountain_biking"/>Mountain Biking
     <input type="checkbox" name="activities[]" value="food"/>Food
     <input type="checkbox" name="activities[]" value="travel"/>Travel<br />
     <input type="checkbox" name="activities[]" value="paintball"/>Paintball
<input type="checkbox" name="activities[]" value="computers"/>Computers
</fieldset>