I have a table users which contains several user information. I'd like to store the user specific permissions in a different table.
Do I need to have the primary key up_id in the user_permissinos table, even if it will not be used anywhere?
I know it is always recommended to have a primary key in a table, but in this case it makes no sense for me. If I need to join both tables I will join up_of_user on user_id.
Table `user`
==========================
user_id int(11) PK AI NN
user_name varchar(50)
...
Table `user_permissions`
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up_id int(11) PK AI NN
up_of_user int(11) FK of user.user_id
up_edit_post tinyint(4) DEFAULT '0'