$query .= " ON DUPLICATE KEY UPDATE first_name = VALUES(first_name), last_name = VALUES(last_name), login = VALUES(login)";
<div class="checklist">
<div class="list-item">
<label for="checkbox_321">
<input id="checkbox_321" type="checkbox" checked="checked">
<p class="list-item-name">dz</p>
</label>
<input type="button" name="details" value="+" >
</div>