Column 'group_id' in where clause is ambiguous. I wonder why?
invoice.php
<?php
//LOAD GROUP
$result2 = mysql_query("SELECT group_name FROM `group`
INNER JOIN invoice
ON `group`.group_id = `invoice`.group_id
WHERE group_id = '".$_GET['group_id']."' ORDER BY group_date") or die(mysql_error());
$result = mysql_query("SELECT * FROM `invoice` WHERE group_id = '".$_GET['group_id']."' ORDER BY group_date ASC") or die(mysql_error());
?>
<?php $data2 = mysql_fetch_array($result2) ?>
Group Name: <?php $data2['group_name']; ?><br><br>