dmark4real: Pls my honorable programmers in the house, i have a problem with the following code: I want the code to calculate the amount whenever the quantity and the rate is selected but i get undefined index and i need the page to automatically calculate and display the amount when the quantity and rate is selected without having to click anything. I hope anyone understand this.


<?php $qty = $_GET['qty'];
$rate = $_GET['rate'];

$amt = ($qty*$rate);


?>
<form action="<?php $_SERVER['PHP_SELF']; ?>" method="get">
<table width="200" border="1">
<tr>
<td>Qty</td>
<td><select name="qty"><option value="1">1</option><option value="2">2</option><option value="3">3</option></select>&nbsp;</td>
</tr>
<tr>
<td>Description</td>
<td><input type="text" name="des" />&nbsp;</td>
</tr>
<tr>
<td>Rate</td>
<td><input type="text" name="rate"/>&nbsp;</td>
</tr>
<tr>
<td>Amount</td>
<td><input type="text" name="amount" value="<?php echo $amt; ?>" />&nbsp;</td>
</tr>
<tr>
<td>&nbsp;</td>
<td><input type="submit" name="submit" value="Save" />&nbsp;</td>
</tr>
</table>


The info will be sent into the database when the button save is clicked.




</form>

<?php 
if(isset($_GET['qty']) && trim($_GET['qty'])!="" && isset($_GET['rate']) && trim($_GET['rate'])!="" )
{
    $qty = (int)$_GET['qty'];
    $rate = (int)$_GET['rate'];
    $amt = ($qty*$rate);

    //<add code to insert to database here>

}

?>

dmark4real: i need the page to automatically calculate and display the amount when the quantity and rate is selected without having to click anything. I hope anyone understand this.

//You'll need JavaScript for it. And maybe AJAX if you eventually want to store the results in your MySql database.
<script>
  calcThis=function(){
    var rate = document.getElementById("rate" ).value ;
    var quantity = document.getElementById("quantity" ).value ;
    var amount = rate * quantity ;
    //OR var amount = (int)(rate) * (int)(quantity) ;
    document.getElementById("amount" ).innerHTML = amount ;
    /*  If you want to store in your MySql database, its more complex: 
    You can define a function tied in to a javascript AJAX library like jquery.js or prototype.js 
    PostViaAjax(rate,quantity,amount) ; */
  }
</script>

<label>Quantity:</label>
  <input value='20' name='quantity' placeholder='quantity' id='quantity' onchange = "calcThis()" />
<br/>
<label>Rate:</label>
  <select onchange = "calcThis()" name='rate' id='rate'>
   <option value='5'>5 Naira</option>
   <option value='10'>10 Naira</option>
  </select>
<br/>
<label>Amount:</label>
  <span id='amount'></span>