Leave Default Option Value Empty In Html Select

I have an html select that is populated with DATA from a query using a foreach loop. It looks something like this $client = $wpdb->get_results('SELECT string FROM `file` WHERE

Solution 1:

Add an empty option first:

echo '<selectname="client_list"><optionvalue=""></option>';

on submit if client_list is empty you know someone didn't choose anything.

Solution 2:

you can use this

$client = $wpdb->get_results("SELECT string FROM `file` WHERE 
     `code` = 002 AND `status` = 2");

    echo'Filter by client: ';
    echo'<select name="client_list"><option value=""></option>';
    foreach ($clientas$key => $row) {
        $value = $row->string;
        echo'<option value='.$value.'>'
        .$value. '</option>';
    }
    $client = $_GET['client_list'];
    echo'</select>';