Comment stocker plusieurs checkbox

	echo "<form method='post' action='resultat.php'>\n";
	echo "<center>";
	echo "<table class=\"green\">";
	echo "<tr><td>Client</td>";
	echo "<td>";
	
	//recuperation de la liste des clients
	$query      = "SELECT id_client, nom_client";
	$query     .= "FROM   clients";
	$query     .= ";";
	//echo "<br>query = $query <br>";
	$result = execute_query($query);
	
	//creation select avec liste des clients
	echo "<select id='id_client' name='id_client'>";
	while($row = mysql_fetch_array($result)) {
		$id_client  = $row[0];
		$nom_client = $row[1];
		echo "	<option value='" . $id_client . "'>" . $nom_client . "</option>";
	}//end while
	echo "</select>";
	echo "</td>";
	echo "</tr>";
	
	
echo "<tr><td></td><td><input  type='submit'></td></tr>\n";
	
	echo "</tr>";
	echo "</td>";
	echo "</table>";
	echo "</form><br/>\n";

if(isset($_REQUEST["id_client"   		])) {$id_client    					= $_REQUEST["id_client"    			];}