จะเขียน check ค่า ถ้าเท่ากับ 0 หรือใส่ค่ามากกว่ามา ให้ alert เเจ้งเตือน

$strSQL = "SELECT * FROM addemployee WHERE Status = '".$_POST['list_status']. "' and  '".$_SESSION["holiday"]."' < 0 ";
$qry = mysql_query($strSQL) or die('Error : '. mysql_error());
$row = mysql_fetch_assoc($qry);	
if($row)
{
echo "<script language=\"JavaScript\">";
echo "alert('ธธธธธธธธธธธธธ');";
echo "window.location='add.php';";
echo "</script>";
}

$strSQL = "SELECT * FROM addemployee WHERE Status = '".$_POST['list_status']. "' 
AND holiday =  '".$_SESSION["holiday"]."' ";
$qry = mysql_query($strSQL) or die('Error : '. mysql_error());
$num = mysql_num_rows($qry);
if($num > 0) {
$row = mysql_fetch_assoc($qry);	
echo "<script language=\"JavaScript\">";
echo "alert('ธธธธธธธธธธธธธ');";
echo "window.location='add.php';";
echo "</script>";
}