This is currently the code I am using:
<?php
//connect to database
include 'global.php';
$case = date(ymdHis);
//get form data
$p1_firstname = addslashes(strip_tags($_POST['p1_firstname']));
$p1_lastname = addslashes(strip_tags($_POST['p1_lastname']));
$p2_firstname = addslashes(strip_tags($_POST['p2_firstname']));
$p2_lastname = addslashes(strip_tags($_POST['p2_lastname']));
$p3_firstname = addslashes(strip_tags($_POST['p3_firstname']));
$p3_lastname = addslashes(strip_tags($_POST['p3_lastname']));
$city = addslashes(strip_tags($_POST['city']));
//register into database
$register_case = mysql_query ("INSERT INTO cases VALUES
('$case','$p1_firstname','$p1_lastname','$city'),
('$case','$p2_firstname','$p2_lastname','$city'),
('$case','$p3_firstname','$p3_lastname','$city')");
?>
The problem with this is that there is often only data for p1. What can I do to check if there is data in a specific name field before inserting it as a row?