MySQL 5.6

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CREATE TABLE tbl_user (
  id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(255) NOT NULL
);

CREATE TABLE tbl_store (
  id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  store VARCHAR(255) NOT NULL
);

CREATE TABLE tbl_user_store (
  id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  fk_user INT NOT NULL,
  fk_store INT NOT NULL,
  FOREIGN KEY (fk_user) REFERENCES tbl_user(id),
  FOREIGN KEY (fk_store) REFERENCES tbl_store(id)
);

CREATE TABLE tbl_article (
  id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  article_name VARCHAR(255) NOT NULL
);

CREATE TABLE tbl_user_entries (
  id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  article_name VARCHAR(255) DEFAULT NULL,

  fk_user INT NOT NULL,
  fk_article INT,
  fk_store INT NOT NULL,
  FOREIGN KEY (fk_user) REFERENCES tbl_user(id),
  FOREIGN KEY (fk_article) REFERENCES tbl_article(id),
  FOREIGN KEY (fk_store) REFERENCES tbl_store(id)
);

INSERT INTO tbl_user (name) VALUES ('Tom'), ('Cendric');
INSERT INTO tbl_store (store) VALUES ('Zurich'), ('Bern'), ('Luzern');
INSERT INTO tbl_user_store (fk_user, fk_store) VALUES (1, 1), (1, 2), (1, 3), (2, 1), (2, 3);
INSERT INTO tbl_article (article_name) VALUES ('article1'), ('article2'), ('article3');
INSERT INTO tbl_user_entries (article_name, fk_user, fk_article, fk_store) VALUES ('article4', 1, NULL, 1), (NULL, 1, 1, 3), (NULL, 1, 2, 2);
SELECT * FROM tbl_user;
SELECT * FROM tbl_store;
SELECT * FROM tbl_user_store;
SELECT * FROM tbl_article;
SELECT * FROM tbl_user_entries;


id
name


1
Tom

2
Cendric




id
store


1
Zurich

2
Bern

3
Luzern




id
fk_user
fk_store


1
1
1

2
1
2

3
1
3

4
2
1

5
2
3




id
article_name


1
article1

2
article2

3
article3




id
article_name
fk_user
fk_article
fk_store


1
article4
1
null
1

2
null
1
1
3

3
null
1
2
2


select u.name,
       coalesce(ue.article_name, a.article_name) article_name,
       s.store store_name
from tbl_user mu 
inner join tbl_user_store mus on mus.fk_user = mu.id
inner join tbl_user_store us on us.fk_store = mus.fk_store
inner join tbl_user u on u.id = us.fk_user 
inner join tbl_store s on s.id = us.fk_store
left join tbl_user_entries ue on ue.fk_user = u.id and ue.fk_store = s.id  
left join tbl_article a on a.id = ue.fk_article
where mu.name = 'Cendric' and coalesce(ue.article_name, a.article_name) is not null


name
article_name
store_name


Tom
article4
Zurich

Tom
article1
Luzern