How do I insert data retrieved from a mysql database back into another table.

<pre><form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post" enctype='multipart/form-data'>
    <p>
        	
		<label for="name">Product Category:</label>
		<?php include 'global.php';
		echo '<select id="category_name" name="category_name">';

  $sql = mysql_query("SELECT category_name FROM tbl_category");
  while ($row = mysql_fetch_array($sql)){
    echo "<option value='".$row['category_name']."'>".$row['category_name']."</option>";
  }
  echo '</select>';
  
  ?>
      <input name="submit" type="submit" class="btn-action" value="Add Product">
</form>

<?php
include 'global.php';
// Escape user inputs for security
$code = mysqli_real_escape_string($link, $_REQUEST['code']);
$name = mysqli_real_escape_string($link, $_REQUEST['name']);
$price = mysqli_real_escape_string($link, $_REQUEST['price']);			
 
// Attempt insert query execution
if(isset($_POST['submit'])) {
		$category_name = $_POST['category_name'];					
				
	//Process the image that is uploaded by the user
    $target_dir = "product/";
    $target_file = $target_dir . basename($_FILES["imageUpload"]["name"]);
    $uploadOk = 1;
	
	$extensions_arr = array("jpg","jpeg","png","gif");
    $imageFileType = pathinfo($target_file,PATHINFO_EXTENSION,$extensions_arr);

    if (move_uploaded_file($_FILES["imageUpload"]["tmp_name"], $target_file)) {
        //echo "The file ". basename( $_FILES["imageUpload"]["name"]). " has been uploaded.";
    } else {
        echo "Issue with image";echo "</br>";
    }
	
    $image=basename($_FILES["imageUpload"]["name"]); // used to store the filename in a variable
			 	
				
            $sql = "insert into tbl_product(code,category_name,name,price,image) 
			values('".$code."','".$name."','".$category_name."','".$price."', '".$target_file."')";
						
						
if(mysqli_query($link, $sql)){
  // Upload file
      
    echo "Product added successfully";
        }
		else{
    echo "" . mysqli_error($link);
}
	}
 
// Close connection
mysqli_close($link); ?>