PHP下拉粘贴

I have a database populated drop down list.

$options4=""; 



    while ($row = mysql_fetch_array($result)) { 

        $id=$row["Client_Code"]; 
        $thing=$row["Client_Full_Name"]; 
        $options4.="<OPTION VALUE=\"$id, $thing\">".$thing; 
    } 
    ?>

    <FORM name="form" action="<?php echo $_SERVER['PHP_SELF']; ?>" method="POST">

    <SELECT NAME="ClientNamefour" OnChange="this.form.submit()">

        <OPTION VALUE=0>Client
        <?php echo $options4?> 

      </SELECT>
    </FORM>

Once this changes it pulls a client name from a database and brings up some information there is a form that can be filled out to insert more information into a database. Once that form is filled out this page sends the information to another page with the code to insert the data into the database. Then I am using a header at the end of that code to send it back to this page. But when it comes back to this page I want it to comeback to the client they selected before and not a blank screen. So how do I make a DB populated list automatically comeback to the previous selection using php?

All you need to do is modify the way you construct the options to spot when you are creating the selected one, then add a SELECTED attribute to it...

    //obtain current value from GET, POST or COOKIE value...
    $current=isset($_REQUEST['ClientNamefour'])?$_REQUEST['ClientNamefour']:'';

    while ($row = mysql_fetch_array($result)) { 

        $id=$row["Client_Code"]; 
        $thing=$row["Client_Full_Name"]; 
        $value="$id, $thing";

        //figure out if we should select this option...
        $sel=($value==$current)?'SELECTED':'';

        $options4.="<OPTION $sel VALUE=\"$value\">".$thing; 
    } 

One way to keep the value persistent would be to store it in the session, e.g. when you process the form

    //assuming session_start() has been called...
    if (isset($_POST['ClientNamefour']))
         $_SESSION['ClientNamefour']=$_POST['ClientNamefour'];