MySQL 8.0

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CREATE TABLE users (
  id_user INTEGER,
  name VARCHAR(8)
);
INSERT INTO users (id_user, name) VALUES
  ('1', 'Paul'),
  ('2', 'Caroline');
CREATE TABLE travel (
  id_travel INTEGER,
  id_user INTEGER
);
INSERT INTO travel (id_travel, id_user) VALUES
  ('1', '1'),
  ('2', '1'),
  ('3', '2');
CREATE TABLE travel_days (
  id_tdays INTEGER,
  id_travel INTEGER,
  day_has_activities VARCHAR(3)
);
INSERT INTO travel_days (id_tdays, id_travel, day_has_activities)
VALUES
  ('1', '1', 'no'),
  ('2', '1', 'no'),
  ('3', '1', 'yes'),
  ('4', '2', 'no'),
  ('5', '2', 'no'),
  ('6', '3', 'no'),
  ('7', '3', 'yes'),
  ('8', '4', 'yes');

Records: 2  Duplicates: 0  Warnings: 0



Records: 3  Duplicates: 0  Warnings: 0



Records: 8  Duplicates: 0  Warnings: 0


SELECT t.id_travel, u.name, td.day_has_activities
FROM travel t
left join users u on u.id_user = t.id_user
left join travel_days td on td.id_travel = t.id_travel


id_travel
name
day_has_activities


1
Paul
yes

1
Paul
no

1
Paul
no

2
Paul
no

2
Paul
no

3
Caroline
yes

3
Caroline
no


SELECT t.id_travel, u.name, max(td.day_has_activities) as has_activities
FROM travel t
left join users u on u.id_user = t.id_user
left join travel_days td on td.id_travel = t.id_travel
group by t.id_travel, u.name


id_travel
name
has_activities


1
Paul
yes

2
Paul
no

3
Caroline
yes