$create_query = qq{
        create table article_event_index(
            id_article int(10) NOT NULL,
            id_event int(10) NOT NULL,
            primary key (id_article, id_event),
            foreign key (id_article) references article (id_article),
            foreign key (id_event) references event (id_event)
        )
    };
    $dbh->do($create_query);