Having worked with large business processes, the "data dictionary" the SQL standard defines is a joke.

The information_schema or any proprietary "db catalog" does not store metadata about an attribute regarding domain, context, roles, dependencies etc. That is why it is just best to use a data modeling tool like Visio combined with a spreadsheet.

--- In firebird-support@yahoogroups.com, "unordained" <unordained_00@...> wrote:
>
> ---------- Original Message -----------
> From: "sqlsvr" <sqlsvr@...>
> > Good practice is using a data dictionary instead of commenting
> > columns/tables directly. Firebird does not have a built-in data
> > dictionary (neither does SQL Server/Oracle).
> ------- End of Original Message -------
>
> "comment on" puts information into the rdb$description field for the appropriate
> rdb$ table for the type of object you're commenting on. As such, it's part of the
> system-provided catalog tables, queriable later, visible in various FB tools,
> kept in sync when you add/drop fields, etc.
>
> Would you like to define "data dictionary", in your opinion? The SQL-92 standard
> mentions a database catalog with specific fields, yes. (SQL-2003 mentions an
> information_schema.) All relational databases at least have their own proprietary
> catalog tables, specific to their feature sets. With Firebird (at least pre-3.0)
> it's even possible to make changes directly in the catalog tables, bypassing DDL
> statements. It's possible to create views on top of those to give you the
> standard ones, but I agree most vendors have not done so. (But then everyone
> feels free to pick and choose the parts of the SQL standard they feel like
> implementing anyway, so I prefer Codd's concept of catalog tables, independent of
> what the SQL committee may have thought "right".) The Interbase6 Language
> Reference guide, in Chapter 7, gives examples of creating such compatibility
> views for constraint tables compatible with those in the SQL-92 spec. See http://
> www.firebirdfaq.org/faq329/ for the download link. It's after figure 7-32.
>
> Also see http://www.petefreitag.com/item/666.cfm for a discussion of what systems
> support what (they say SQLServer 7+ supports information_schema outright), and in
> the comments, you'll find a link to http://www.alberton.info/
> firebird_sql_meta_info.html ; he has scripts for other databases too, to bring
> them all in line with each other.
>
> -Philip
>