[thelist] Constraint/trigger help

Bill Moseley moseley at hank.org
Fri May 18 01:17:23 CDT 2007

Say I have a mail reader application where people can create their own
mailboxes (folders).  So I have a table:

    create table mailbox (
        id       integer,
        name     text,
        owner    int references user(id)

So, now the user table should store their default mailbox
(ignoring that I've referenced user above before defining it)

    create table user (
        id               integer,
        name             text,
        email            text,
        default_mailbox  integer references mailbox(id)

How can I ensure (in the database) that default_mailbox references a
mailbox that has its owner set to the same user?  Obviously, don't
want one user's default mailbox to reference another user's mailbox.

I'm not thrilled by the circular references there.

Bill Moseley
moseley at hank.org

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