How to get all projects that do not have a connection with a certain user through 2 tables?

Question

SQL

2 tables: project, project_user
I want to get all projects that do not have a connection with id 4 for example, even if this project has a connection with another user (that is, it has a connection with id 4 and id 5), I do not want to receive this project at all, despite the 5.

Answer 1

i want to get all projects that have no connection with id 4

SELECT p.*
FROM project p
WHERE NOT EXISTS ( SELECT NULL
                   FROM project_user u
                   WHERE p.project_id = u.project_id
                     AND u.user_id = 4 )

Answer 2

... where project.id NOT IN (
  select distinct project_id from project_user where user_id=4
)