[php] PHP checkbox set to check based on database value

I have a system where people fill in their information and later can go back and edit certain parts, basically the enter personal info and check whether they want to know extra info, these bits of extra infos are checkboxes, 4 of them. the user will select up to any of the 4 and the database has 4 fields set to no, if they select one it changes to yes. I want them to be able to go back and deselect or reselect any of these 4 checkboxes, so what i want s for the checkboxes to be selected if the values is yes and unselected if the value is not.

the fields are tag_1, tag_2, tag_3, tag_4

Anyhelp greatly appreciated

I gather some kind of if statement but not sure how to involve it in a checkbox.

<label for="tag_1">Tag 1</label>
<input type="checkbox" name="tag_1" id="tag_1" value="yes" />

Ian

You can read database value in to a variable and then set the variable as follows

$app_container->assign('checked_flag', $db_data=='0'  ? '' : 'checked');

And in html you can just use the checked_flag variable as follows

<input type="checkbox" id="chk_test" name="chk_test" value="1" {checked_flag}>

Use checked="checked" attribute if you want your checkbox to be checked.

This simplest ways is to add the "checked attribute.

<label for="tag_1">Tag 1</label>
<input type="checkbox" name="tag_1" id="tag_1" value="yes" 
    <?php if($tag_1_saved_value === 'yes') echo 'checked="checked"';?> />

Add this code inside your input tag

<?php if ($tag_1 == 'yes') echo "checked='checked'"; ?>