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create table user (user_id int primary key, name varchar(255));
create table post (post_id int primary key, user_id int, txt varchar(255));
insert into user (user_id, name) values
(1, 'User 1'),
(2, 'User 2'),
(3, 'User 3'),
(4, 'User 4');
insert into post (post_id, user_id, txt) values
(1, 1, 'Post 1 of User 1'),
(2, 1, 'Post 2 of User 1'),
(3, 3, 'Post 3 of User 3'),
(4, 6, 'Post 4 of User 6'),
(5, 7, 'Post 5 of User 7');
select * from user;
select * from post;
| user_id | name |
|---|---|
| 1 | User 1 |
| 2 | User 2 |
| 3 | User 3 |
| 4 | User 4 |
| post_id | user_id | txt |
|---|---|---|
| 1 | 1 | Post 1 of User 1 |
| 2 | 1 | Post 2 of User 1 |
| 3 | 3 | Post 3 of User 3 |
| 4 | 6 | Post 4 of User 6 |
| 5 | 7 | Post 5 of User 7 |
SELECT COALESCE(user.name, 'Anonymous') name,
post.txt
FROM post
LEFT JOIN user USING (user_id)
| name | txt |
|---|---|
| User 1 | Post 1 of User 1 |
| User 1 | Post 2 of User 1 |
| User 3 | Post 3 of User 3 |
| Anonymous | Post 4 of User 6 |
| Anonymous | Post 5 of User 7 |