my %sql = ('experience.country' =>  q#JOIN has_regional_experience ON people.ID_person = has_regional_experience.ID_person
        JOIN countries AS experience ON has_regional_experience.ID_country = experience.ID_country        
        #,
        'nationality.country' => q#JOIN belongs_to ON people.ID_person = belongs_to.ID_person
        JOIN countries AS nationality ON belongs_to.ID_country = nationality.ID_country        
        #,
        'expertise' => q#JOIN owns ON people.ID_person = owns.ID_person
        JOIN expertise ON owns.ID_expertise = expertise.ID_expertise        
        #,
        'language' => q#JOIN spoke ON people.ID_person = spoke.ID_person
        JOIN languages ON spoke.ID_language = languages.ID_language        
        #,
        'donor' => q# JOIN worked_for ON people.ID_person = worked_for.ID_person
        JOIN donors ON worked_for.ID_donor = donors.ID_donor    
        #);

    $sqlquery .= $sql{$self->{field1}}.$sql{$self->{field2}}.$sql{$self->{field3}}