I do not understand what's happening. I have a query in PHP who crashes -with a strange error-. When I copy/paste the exact same request in PHPMyAdmin it works as expected. What am I doing wrong here ?

 SELECT oms_patient.id,
       oms_patient.date,
       oms_patient.date_modif,
       date_modif,
       AES_DECRYPT(nom,"xxxxx") AS "Nom",
       AES_DECRYPT(prenom,"xxxxx") AS "Prénom usuel",
       DATE_FORMAT(ddn, "%d/%m/%Y") AS "Date de naissance",
       villeNaissance AS "Lieu de naissance (ville)",
       CONCAT(oms_departement.libelle,"(",id_departement,")") AS "Lieu de vie",
       CONCAT(oms_pays.libelle,"(",id_pays,")") AS "Pays",
       CONCAT(patientsexe.libelle,"(",id_sexe,")") AS "Sexe",
       CONCAT(patientprofession.libelle,"(",id_profession,")") AS "Profession",
       IF(asthme>0,"Oui","Non") AS "Asthme",
       IF(rhinite>0,"Oui","Non") AS "Rhinite",
       IF(bcpo>0,"Oui","Non") AS "BPCO",
       IF(insuffisanceResp>0,"Oui","Non") AS "Insuffisance respiratoire chronique",
       IF(chirurgieOrl>0,"Oui","Non") AS "Chirurgie ORL du ronflement",
       IF(autreChirurgie>0,"Oui","Non") AS "Autre chirurgie ORL",
       IF(allergies>0,"Oui","Non") AS "Allergies",
       IF(OLD>0,"Oui","Non") AS "OLD",
       IF(hypertensionArterielle>0,"Oui","Non") AS "Hypertension artérielle",
       IF(infarctusMyocarde>0,"Oui","Non") AS "Infarctus du myocarde",
       IF(insuffisanceCoronaire>0,"Oui","Non") AS "Insuffisance coronaire",
       IF(troubleRythme>0,"Oui","Non") AS "Trouble du rythme",
       IF(accidentVasculaireCerebral>0,"Oui","Non") AS "Accident vasculaire cérébral",
       IF(insuffisanceCardiaque>0,"Oui","Non") AS "Insuffisance cardiaque",
       IF(arteriopathie>0,"Oui","Non") AS "Artériopathie",
       IF(tabagismeActuel>0,"Oui","Non") AS "Tabagisme actuel",
       CONCAT(nbPaquetsActuel," ","PA") AS "",
       IF(tabagismeAncien>0,"Oui","Non") AS "Tabagisme ancien",
       CONCAT(nbPaquetsAncien," ","PA") AS "",
       IF(alcool>0,"Oui","Non") AS "Alcool (conso régulière)",
       IF(refluxGastro>0,"Oui","Non") AS "Reflux gastro-oesophagien",
       IF(glaucome>0,"Oui","Non") AS "Glaucome",
       IF(diabete>0,"Oui","Non") AS "Diabète",
       CONCAT(patienttypeDiabete.libelle,"(",id_typeDiabete,")") AS "",
       IF(hypercholesterolemie>0,"Oui","Non") AS "Hypercholestérolémie",
       IF(hypertriglyceridemie>0,"Oui","Non") AS "Hypertriglycéridémie",
       IF(dysthyroidie>0,"Oui","Non") AS "Dysthyroïdie",
       IF(depression>0,"Oui","Non") AS "Dépression",
       IF(sedentarite>0,"Oui","Non") AS "Sédentarité",
       IF(syndromeDApneesSommeil>0,"Oui","Non") AS "SAS",
       IF(obesite>0,"Oui","Non") AS "Obésité",
       IF(dysmorphieFaciale>0,"Oui","Non") AS "Dysmorphie faciale",
       TextObservations AS "",
       id_user
FROM oms_patient
LEFT JOIN oms_departement ON oms_departement.id = id_departement
LEFT JOIN oms_pays ON oms_pays.id = id_pays
LEFT JOIN patientsexe ON patientsexe.id = id_sexe
LEFT JOIN patientprofession ON patientprofession.id = id_profession
LEFT JOIN patienttypeDiabete ON patienttypeDiabete.id = id_typeDiabete
WHERE oms_patient.id=1

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'small">(conso régulière)", IF(refluxGastro>0,"Oui","Non") as "Reflux ga' at line 1

"near 'small" <-- where is small o_O

The PHP code isn't really relevant cause you won't see a lot.

  $db = mysql_connect();
    mysql_select_db();//TODO SWITCH TO PDO
    mysql_query("SET NAMES UTF8");


    $fields = $form->getFields($form);
    $settingsForm = $form->getSettings();
    $sql = 'SELECT oms_patient.id,oms_patient.date,oms_patient.date_modif,';
    foreach ($fields as $field) {
        if (!$field->isMultiSelect()) {
            $field->select_full(&$sql, 'oms_patient', null);
        }
    }
    if (isset($settingsForm['linkTo'])) {
        $idLinkTo = 'id_' . str_replace('oms_', '', $settingsForm['linkTo']);
        $sql .= $idLinkTo;
    }

    $sql.=' FROM oms_patient';
    foreach ($fields as $field) {
        if (!$field->isMultiSelect() && $field->getTable('oms_patient')) {
            $sql .=' LEFT JOIN ' . $field->getTable('oms_patient') . ' ON ' . $field->getTable('oms_patient') . '.id = '.$field->getFieldName().' ';
        }
    }
    $sql.=' where oms_patient.id=' . $this->m_settings['e'];

    $result = mysql_query($sql) or die('Erreur SQL !<br>' . $sql . '<br>' . mysql_error());
    $data = mysql_fetch_assoc($result);

var_dump of $sql

string(2663) "SELECT oms_patient.id,oms_patient.date,oms_patient.date_modif,date_modif,AES_DECRYPT(nom,"xxxxx") as "Nom",AES_DECRYPT("prenom","xxxxx") as "Prénom usuel",DATE_FORMAT(ddn, "%d/%m/%Y") as "Date de naissance",villeNaissance as "Lieu de naissance (ville)",CONCAT(oms_departement.libelle,"(",id_departement,")") as "Lieu de vie",CONCAT(oms_pays.libelle,"(",id_pays,")") as "Pays",CONCAT(patientsexe.libelle,"(",id_sexe,")") as "Sexe",CONCAT(patientprofession.libelle,"(",id_profession,")") as "Profession", IF"...

can't go further to see what is in the output after the "..." <-- if you have an idea