if(isset($_POST['addproduct'])) {
$product = new product(0,$_POST['productName'],$_POST['productDescription'],$_POST['productVersion'])  ;
addProduct($product,$con,$modules);
addproductmodule($modules,$con,$productId);
$modules=$_POST['modules'];
}
function addproduct(Product $product, Connection $con,$modules){
  $sql = ("INSERT INTO products (productName,productDescription,productVersion) values(?,?,?)");
$req=$con->getPdo()->prepare($sql);
$req->execute(array($product->getProductName(),$product->getProductDescription(),$product->getProductVersion()));

function addproductmodule($modules,  Connection $con, $productId){        $productId=$con->getPdo()->lastInsertId();
foreach ($modules as $value)
{$rq = "INSERT INTO product_module (productId, moduleId) VALUES (.'$productId'., .'$value'.)";
$rep=$con->getPdo()->prepare($rq);
$rep->execute(array());  }

<form class="form-horizontal " method="POST">
<div class="form-group">
<label for="productName" class="col-sm-3 control-label">Product name : <span class="required" style="color:red;">*</span></label>
<div class="col-sm-9">
<input type="text" id="productName" class="form-control" name="productName" value="" required="required" />
</div>
</div>
<div class="form-group">
<label for="productDescription" class="col-sm-3 control-label">Product description : <span class="required" style="color:red;">*</span></label>
<div class="col-sm-9">
<textarea id="productDescription" class="form-control" name="productDescription"  required="required" > </textarea>
</div>
</div>
<div class="form-group">
<label for="productVersion" class="col-sm-3 control-label">Product version     <span class="required" style="color:red;">*</span></label>
<div class="col-sm-9">
<input type="text" id="productVersion" class="form-control" name="productVersion" value="" required="required" />
</div>
</div>

<?php
$modules=ViewModules($con);
$count=count($modules);
$data='<div class="form-group"><label for="productModules" class="col-sm-3 control-label">Product modules : <span class="required" style="color:red;">*</span></label>
<div class="col-sm-3">
<select id="select1"class="form-control"  multiple size="'.$count.'"style="height:100px;">';
if ($count>0){
$number=1;
foreach ($modules as $module)
{$data .='<option value="'.$module['moduleId'].'">'.$module['moduleName'].'</option>';

$number++;
}}
else {$data .='<option value="Please add modules first">Please add modules first</option>
</br>';}

$data .= '</select><a href="#" id="add">add >></a></div><div class="col-sm-3">
<select multiple="multiple" name="modules" id="select2" class="form-control" style="height:100px;"></select>
<a href="#" id="remove"><< remove</a>
</div></div><br>';
echo $data;

?>
<br>

<center><input type="submit" class="btn btn-primary" style="width:10%;" name="addproduct" value="Save"/></center>
</form>