[thelist] Constraint/trigger help

Jeffrey Barke jeffrey.barke at themechanism.com
Fri May 18 09:57:09 CDT 2007


Instead of storing the default mailbox in the user table, you could  
add a boolean field in the mailbox table to indicate default status.  
This would solve your integrity and circular reference concerns.


Jeffrey Barke
jeffery.barke at theMechanism.com
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Blah, blah, blah...

On May 18, 2007, at 2:17 AM, Bill Moseley wrote:

> 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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