create table article
(
    id      int
        constraint article_pk
            primary key,
    subject text,
    body    text
);

create table tag
(
    id   int
        constraint tag_pk
            primary key,
    name text

);

create table article_tag
(
    tag_id     int,
    article_id int

);

SELECT a.subject, t.name
FROM article a
LEFT JOIN article_tag at ON a.id = at.article_id
LEFT JOIN tag t ON t.id = at.tag_id