Recherche avancée.

Bonjour,
j'ai un problème avec recherche avancer composer de plusieurs tables


$req=$dbh->query("SELECT * FROM sujet where titre_suj like '%".$rech."%' OR id_ens=(SELECT id_ens FROM enseignant
WHERE nom like '%".$rech."%') OR id_etud=(SELECT id_etud FROM etudiant WHERE nom like '%".$rech."%' OR id_etab=(SELECT id_etab FROM etablissement WHERE nom_etab ike '%".$rech."%') OR id_uni =(SELECT id_uni FROM uiversite WHERE nom_uni ike '%".$rech."%') OR theme=(SELECT id_th FROM theme WHERE nom_th like '%".$rech."%') OR id_sth =(SELECT id_sth FROM soustheme WHERE nom_sth like '%".$rech."%') OR cycle =(SELECT id_cycle FROM cycle WHERE nom_cycle like '%".$rech."%') OR domaine =(SELECT id_domaine FROM domaine WHERE nom_domaine like '%".$rech."%')");
}
elseif ($v=='1')
{
$req=$dbh->query("SELECT * FROM `sujet` where `titre_suj` like '%".$sujet."%' AND `id_ens`=(SELECT `id_ens` FROM `enseignant`
WHERE `nom` like '%".$ens."%') AND `id_etud`=(SELECT `id_etud` FROM `etudiant` WHERE `nom` like '%".$etud."%' AND `id_etab`=(SELECT `id_etab` FROM `etablissement` WHERE `nom_etab` ='$etab') AND `id_uni` =(SELECT `id_uni` FROM `uiversite` WHERE `nom_uni` ='$uni') AND `theme`=(SELECT `id_th` FROM `theme` WHERE `nom_th` like '%".$th."%') AND `id_sth` =(SELECT `id_sth` FROM `soustheme` WHERE `nom_sth` like '%".$sous_th."%') AND `cycle` =(SELECT `id_cycle` FROM `cycle` WHERE `nom_cycle` like '%".$cycle."%') AND `domaine` =(SELECT `id_domaine` FROM vdomaine` WHERE `nom_domaine` like '%".$domaine."%')");