Is this hard core rule that left and right join are perfectly one to many relationship???
I ask this because while we interchange Departments_dup and dept_manager_dup table in left join than how this relationship gone be one to many. This must be many to one after interchange
I think it's not a hard rule. However, the lecture present that when we have two tables A and B, then A LEFT JOIN B would be exactly the same as B RIGHT JOIN A. Hence, dept_manager_dup LEFT JOIN departments_dup and the interchanged position of tables in departments_dup RIGHT JOIN dept_manager_dup are both many-to-one relationship (with respect to dept_manager_dup being on the left side of the relation).
I created a chart for reference. You can see that in both joins, dept_manager_dup is the highlighted area.
Hi Mayank and Carl!
Thanks for reaching out.
Thanks for sharing this piece of information with the Community!
It is not a rule, it depends on the task. You have to define the case of the task and decide the appropriate relationship.
Hope this helps.