PHP - Multiple Selections From Drop Down Lists To Create A Mysql Select Command

Hi I have tried the mysql forum but have had no joy with an answer to my problem so wondered if php would be better.

I want my users to be able to select from 5 different drop down lists where they can chose any combination from 1 up to all 5,  I have attached the front end.  These lists are being populated from mysql tables.

Code for the drop down lists is as follows
Code: [Select]
  <form action="horse-events-devon.php?url_countyid=<?php echo  urlencode ($url_countyid ['url_countyid'])  ; ?>&go" method="POST">
    <table id="searchtable">
      <tr>
        <th>Find By Discipline</th>
        <th>Find By Venue</th>
        <th>Find By Championship</th>
        <th>Find By Organiser</th>
        <th>Equine Association</th>
        <th>Submit Your Selections</th>
        </tr>
      <tr>
        <td><select name="dis_id">
                                    <?php 
                                        $upcomingdis = upcomingdis($url_countyid);
                                        $upcoming_dis_bycounty = mysql_fetch_assoc ($upcomingdis);
                                    ?>
                                    <?php 
                                    do { 
       ?>   <option value="<?php echo $upcoming_dis_bycounty ['dis_id']; ?>" >
<?php echo $upcoming_dis_bycounty ['dis_description']; ?></option>
<?php 
                                    } while ($upcoming_dis_bycounty = mysql_fetch_assoc ($upcomingdis)); 
                                    ?></select></td>
        <td><select name="ven_id">
                                    <?php 
                                        $upvenbycounty_set = upcoming_venevents_bycounty($url_countyid);
                                        $upcoming_ven_bycounty = mysql_fetch_assoc ($upvenbycounty_set);
                                    ?>
                                    <?php 
                                    do { 
       ?>   <option value="<?php echo $upcoming_ven_bycounty ['ven_id']; ?>" >
<?php echo $upcoming_ven_bycounty ['ven_name']; ?></option>
<?php 
                                    } while ($upcoming_ven_bycounty = mysql_fetch_assoc ($upvenbycounty_set)); 
                                    ?></select></td>
        <td><select name="champ_id">
                                    <?php 
                                        $championship_set = findchampionships();
                                        $champlist = mysql_fetch_assoc ($championship_set);
                                    ?>
                                    <?php 
do { 
?>   <option value="<?php echo $champlist ['champ_id']; ?>" >
<?php echo $champlist ['champ_description']; ?></option>
<?php 
} while ($champlist = mysql_fetch_assoc ($championship_set)); 
?></select></td>
        <td>
        <select name="org_id">
                        <?php 
                            $uporgbycounty_set = upcoming_organevents_bycounty($url_countyid);
                            $upcoming_org_bycounty = mysql_fetch_assoc ($uporgbycounty_set);
                        ?>
                        <?php 
                        do { 
                        ?>   <option value="<?php echo $upcoming_org_bycounty ['org_id']; ?>" ><?php echo $upcoming_org_bycounty ['org_name']; ?></option>
                        <?php 
                        } while ($upcoming_org_bycounty = mysql_fetch_assoc ($uporgbycounty_set)); 
                        ?></select>
       
        </td>
        <td><select name="ass_id">
                                    <?php
                                        $upassbycounty_set = upcoming_assevents_bycounty($url_countyid);
                                        $upcoming_assbycounty = mysql_fetch_assoc ($upassbycounty_set);
                                    ?>
                                    <?php 
                                    do { 
                                    ?>   <option value="<?php echo $upcoming_assbycounty ['ass_id']; ?>" >
<?php echo $upcoming_assbycounty ['ass_description']; ?></option>
                                    <?php 
                                    } while ($upcoming_assbycounty = mysql_fetch_assoc ($upassbycounty_set)); 
                                    ?></select></td>
      <td><input name="submit" type="submit" /><input name="countyid" type="hidden" value="<?php echo $url_countyid ['url_countyid']; ?>" /></td>
        </tr>
      </table>
  </form>
My search processing is as follows

Code: [Select]
  <?php
if (isset($_POST['submit'])){
if (isset($_GET['go'])){
$countyid = $_POST['countyid'];
$ven_id = $_POST['ven_id'];
$dis_id = $_POST['dis_id'];
$champ_id = $_POST['champ_id'];
$org_id = $_POST['org_id'];
$event_id = $row['event_id'];

$sql = "SELECT DATE_FORMAT (events.startdate, '%a, %d, %b') 
   AS stdate, events.event_id, events.title, events.ven_id, events.org_id,
   venue.county_id, venue.ven_id, eventdisciplines.event_id, eventdisciplines.dis_id, county.county_id, discipline.dis_id \n"
. "FROM events \n"
. "LEFT OUTER JOIN eventdisciplines \n"
. "ON events.event_id = eventdisciplines.event_id \n"
. "LEFT OUTER JOIN discipline \n"
. "ON eventdisciplines.dis_id = discipline.dis_id \n"
. "LEFT OUTER JOIN venue \n"
. "ON events.ven_id = venue.ven_id \n"
. "LEFT OUTER JOIN county \n"
. "ON venue.county_id = county.county_id \n"
. "WHERE events.ven_id = ({$ven_id} OR events.org_id = {$org_id})\n"
. "AND events.startdate > NOW()\n"
. "AND venue.county_id = {$countyid}  \n"
. "ORDER BY startdate ASC";

$result = mysql_query ($sql, $connection);
?>
How am I best to do this please?  my OR within the mysql does not work, should I not be doing this with php in the search processing?  someones help would really be appreciated, just to point me in the right direction.

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