如何在PHP页面中添加Ajax

I am not familiar with ajax. pls help me how i can do in script Below my script and using pdo and mssql 2005. Below script working fine. But everytime change the details, page refresh and display is delayed

Pls help me

index.php

<?php
include_once '../inc/connection.inc.php';
?>

<?php
try {
       $stmt = $dbh->prepare('SELECT * FROM MVendorMaster order by MVName');
       $stmt->execute();
    } 
catch (PDOException $e) 
    {
       $output = 'Error fetching main vendor from database!';
   include '../errormsg.php';
       exit();
    }

foreach ($stmt as $row) 
    {
       $mvcode[] = array('MVCode' => $row['MVCode'], 'MVName' => $row['MVName']);
    }
include 'searchform.html.php';
?>

<?php
if (isset($_POST['mvendor']) && $_POST['mvendor']  != "" )
{
    $mvcode = $_POST["mvendor"];
$datefrom=$_POST["datefrom"];
$dateto=$_POST["dateto"];

$stmt = $dbh->query("SELECT * FROM InvoiceHead WHERE MVCode='$mvcode' and SODate>='$datefrom' and SODate<='$dateto' order by SODate");  
    $stmt->setFetchMode(PDO::FETCH_ASSOC);  
 }
include 'view.html.php';
    exit();

?>

searchform.html.php

<?php
include '../templete/header.php';
?>

<form action="" method="post">
<table>
  <tr>
  <td>Main Vendor Name </td>
  <td>
  <select name="mvendor" id="mvcode"><option value="">Mian Vendor</option>
<?php foreach ($mvcode as $mvcodes): ?>
<option value="<?php htmlout($mvcodes['MVCode']); ?>">
<?php htmlout($mvcodes['MVName']); ?></option>
<?php endforeach; ?>
</select>

  </td>

  </tr>
  <tr>
<td>Date[From]:</td>
<td><input type="text" id="datepicker1" name="datefrom" /></td>
  </tr>
  <tr>
<td>Date[To]:</td>
<td><input type="text" id="datepicker2" name="dateto" /></td>
  </tr>    
</table>

<div>

<input type="submit" value="Search">
</div>
</form>

view.html.php

<?php //include '../templete/header.php'; ?>
<script language="javascript" type="text/javascript">
 //window.print();
</script>

<script type="text/javascript">

function PrintGridData() {
    var prtGrid = document.getElementById('<%=txtDocNo%>');
prtGrid.border = 0;
var prtwin = window.open('', 'PrintGridViewData', 'left=100,top=100,width=1000,height=1000,tollbar=0,scrollbars=1,status=0,resizable=1');
            prtwin.document.write(prtGrid.outerHTML);
            prtwin.document.close();
            prtwin.focus();
            prtwin.print();
            prtwin.close();
 </script>

<table width="100%" align="center" cellpadding="4" cellspacing="1" class=tbl_table">
  <tr>
    <td class="tbl_header">MV CODE</td>
    <td class="tbl_header">MV NAME</td>
    <td class="tbl_header">SONO</td>
    <td class="tbl_header">SO Date</td>
    <td class="tbl_header">RATE</td>
    <td class="tbl_header">SUPP.QTY</td>
    <td class="tbl_header">RTN.QTY</td>
    <td class="tbl_header">BAL.Qty</td>
    <td class="tbl_header">SOLD AMT</td>



    <td class="tbl_header">Actions</td>


  </tr>
<?php 

if(isset($stmt))
    { 
        while($row = $stmt->fetch())
    {?>
<tr>
  <td class="tbl_content"><?php echo $row['MVCode'];?></td>
  <td class="tbl_content"><?php echo $row['MVName'];?></td>
  <td class="tbl_content"><?php echo $row['SONo'];?></td>
  <td class="tbl_content"><?php echo date("d-m-Y", strtotime($row['SODate']));?></td>
  <td class="tbl_content_right"><?php echo number_format($row['Rate'],2) ;?></td>
  <td class="tbl_content_right"><?php echo number_format($row['Qty']) ;?></td>
  <td class="tbl_content_right"><?php echo number_format($row['RTNQty']) ;?></td>
  <td class="tbl_content_right"><?php echo number_format($row['BalQty']) ;?></td>
  <td class="tbl_content_right"><?php echo number_format($row['BalAmt'],2) ;?></td>
  <!--number_format
  <td>
      <a href="view?=<?php echo $row['SVCode'];?>">View</a> |
      <a href="edit?=<?php echo $row['SVCode'];?>">Edit</a> |
      <a href="delete?=<?php echo $row['SVCode'];?>">Delete</a>
  </td>
-->
</tr>
<?php }}?> 
</table>

<?php unset($dbh); unset($stmt); ?>

<?php
include '../templete/footer.php';
?>    

Data connection

<?php
  try {
        $hostname = "server";            //host
$dbname = "db1";            //db name
$username = "sa";            // username like 'sa'
$pw = "gdte56fh5&^4T$";                // password for the user
$dbh = new PDO ("mssql:host=$hostname;dbname=$dbname","$username","$pw");
    } 

  catch (PDOException $e) 
    {
        echo "cannot connect " . $e->getMessage() . "
";
file_put_contents('PDOErrors.txt', $e->getMessage(), FILE_APPEND);
    exit;
}
?>

Pls help how can i add ajax in this page

thanking you

maideen

see my answer in this page. Its quite basic and easy example. stackoverflow.com/questions/16412321/how-do-you-take-data-from-form-element-select-with-option-into-php-on-form-s/16412364#16412364