Mon requete de recherche dans la DB n'affiche rien

<div>
<form name="recherche" action="reqrech.php" method="POST">
    <table>
	    <tr>
		    <td><div align="center"><input type="submit" value="Rechercher"</div></td>
		    <td><div align="center"><input type="search" name="search"/></div></td>
			<td><div align="center">nom<input type="checkbox" name="coche[]" value="nom_user"/></div></td>
			<td><div align="center">prénom<input type="checkbox" name="coche[]" value="prenom_user"/></div></td>
			<td><div align="center">adresse<input type="checkbox" name="coche[]" value="adresse_user"/></div></td>
			<td><div align="center">tel<input type="checkbox" name="coche[]" value="tel_user"/></div></td>
			<td><div align="center">atelier<input type="checkbox" name="coche[]" value="atelier_user"/></div></td>
			<td><div align="center">mail<input type="checkbox" name="coche[]" value="mail_user"/></div></td>
			<td><div align="center">fb<input type="checkbox" name="coche[]" value="fb_user"/></div></td>
			<td><div align="center">service<input type="checkbox" name="coche[]" value="service_user"/></div></td>
		<tr>
	</table>
</form>
</div>

<?php
include("../connect.php");
$coche = NULL;
$sql = NULL;
$search = $_POST['search'];
if(isset($_POST['coche'])){
    foreach ($_POST['coche'] as $coche){
	    $sql="SELECT * FROM utilisateur WHERE '".$coche."' LIKE '".$search."%'";
	}
}
$requete = mysql_query( $sql, $cnx ) or die( "ERREUR MYSQL numéro: ".mysql_errno()."<br>Type de cette erreur: ".mysql_error()."<br>\n" );

echo "<table border=\"3\" cellpadding=\"5\" cellspacing=\"1\" align=\"center\">\n" ;
echo "<tr>
<td><div align=\"center\">id</div></td>
<td><div align=\"center\">Nom</div></td>
<td><div align=\"center\">Prénom</div></td>
<td><div align=\"center\">Adresse</div></td>
<td><div align=\"center\">Tel</div></td>
<td><div align=\"center\">Atelier</div></td>
<td><div align=\"center\">Email</div></td>
<td><div align=\"center\">Facebook</div></td>
<td><div align=\"center\">Service</div></td>
</tr>" ;

while($result = mysql_fetch_array($requete))
{
echo "<tr>\n";
echo "<td><div align=\"center\">".$result["id_user"]."</div></td>\n" ;
echo "<td><div align=\"center\">".$result["nom_user"]."</div></td>\n" ;
echo "<td><div align=\"center\">".$result["prenom_user"]."</div></td>\n" ;
echo "<td><div align=\"center\">".$result["adresse_user"]."</div></td>\n" ;
echo "<td><div align=\"center\">".$result["tel_user"]."</div></td>\n" ;
echo "<td><div align=\"center\">".$result["atelier_user"]."</div></td>\n" ;
echo "<td><div align=\"center\">".$result["mail_user"]."</div></td>\n" ;
echo "<td><div align=\"center\">".$result["fb_user"]."</div></td>\n" ;
echo "<td><div align=\"center\">".$result["service_user"]."</div></td>\n" ;
echo "<td><div align=\"center\"><a href=\"formmodification.php?idUser=".$result['id_user']."\">Modifier</a></div></td>\n";
echo "<td><div align=\"center\"><a href=\"supprimer.php?idUser=".$result['id_user']."\">Supprimer</a></div>\n";
echo "</tr>\n" ;
}
echo "</table><br>\n" ;
?>

<?php
$cnx = mysql_connect( "localhost", "root", "" );
$db= mysql_select_db( "maintenanceinfo" );
?>