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That's irrelevant though. I was talking about the database at the logical level. The point of Physical Data Independence is that the internals of the database in memory and on disk are hidden from the user and are not relevant to a discussion about logical database design. Strange as it seems...

The idea of any tables being "linked" other than in the mind of the user is entirely contrary to the relational model of data. As I expect you might know, Codd's relational model was designed to abolish from the database any kind of structures linking tables together and to remove the need for...

You mean BCNF? 5NF? Something else? These sound like functional requirements rather than anything much to do with normalization. I.e.: If you require unique names then you require some way of eliminating duplicates from your system. If you need to store multiple phone numbers, emails...

ALTER TABLE ... ADD CONSTRAINT ... FOREIGN KEY is the tool for enforcing RI. You need to use the InnoDB engine to get foreign key support. http://dev.mysql.com/doc/refman/5.5/en/alter-table.html

Nullable foreign keys are definitely part of standard SQL but in Oracle or SQL Server their default behaviour is different to Jet/ACE (not sure about MySQL or PostgreSQL). Try the following in SQL Server and you'll find that the row insert succeeds. Try applying the same constraint in Jet/ACE...

Setting a column to be Required=No means that the attribute is nullable (nulls are permitted). I suggest you avoid allowing nulls in foreign key columns. A null foreign key means that the constraint is not enforced and this has disadvantages. Queries that expect the constraint to be enforced...

Dave, I registered here in April 2009 and have 49 posts according to my profile. I think that makes me an infrequent poster. I reopened this thread only because it appears second from the top when I Google for Candidate Key. So I thought it deserved a better explanation.

A bit late, but... A primary key is a candidate key. There is no difference. By common convention one candidate key is designated as a "primary" one and that key is used for any foreign key references. In practice however, that's really a point of convenience for database developers and it...

Sounds like a non-key dependency to me (room->building) which would violate Boyce Codd Normal Form. Sound database design has nothing to do with user interface design. Get the data model right and then concern yourself with how to display it on a form.

namliam, I think you may be confusing 5NF and BCNF with something else. BCNF and 5NF are by definition a "stronger" form of normalization than 3NF. In other words if a database is in 5NF or BCNF it is already in 3NF. This is implicit in their definitions. BCNF was a further refinement of 3NF...

I think I can guess what you are trying to say but what you actually said is a bit misleading. Any schema with any given set of dependencies can be normalized into Boyce Codd, 5th or any other Normal Form. It's true that in some cases you may have to lose some dependencies from the final model...

Normalization is concerned with dependencies within tables, not between them. It's difficult or impossible to give specific design advice in a forum without being familiar with your particular situation. Having said that, nothing you've said seems to indicate anything "wrong" with your design...

Only to the extent that it explains a different set of assumptions from mine. The way I read it the OP is not trying to break or usurp the key constraint at all. He specifically says he wants to enforce it and that therefore he needs to make sure he only inserts a selection of rows which do not...

In what way would that help? You would still want some method of removing the duplicates when doing the insert - the surrogate key won't do that for you. You would then have two keys instead of one, which isn't necessarily a bad thing but it doesn't actually solve any problem it just adds some...

The IGNORE_DUP_KEY option isn't generally a good idea. For one thing the results are unpredictable. If you attempt to insert multiple rows with the same key then one arbitrarily selected row will be inserted and the rest silently ignored. In most cases the desired result is to prevent the...

Looks to me like one table with two attributes (RefA and RefB). (RefA,RefB) would be the key as well.

Glad you got it working. SSE definitely does support views. Even indexed views are supported (you won't get query rewrites against indexed views but that isn't likely to be a problem in Express). No import conversion is needed for Express because it uses exactly the same file format as other...

Have you asked for help in a SQL Server forum like SQLServerCentral.com? I've installed SQL Server Express many times and I don't think it has ever taken more than 10 minutes.

2008 for sure. The improvements to the management and dev tools alone are worth it over 2005. No point upgrading to an old version. PS. Just to add another option to your list, 2008 R2 is out soon. But unless you need any of its BI enhancements I wouldn't bother waiting for it.

I don't quite see what the problem is. SQL Server Express takes less time to install than it must have taken to type your messages in this thread. Even SQL Server Dev Edition takes only a few minutes for a minimal install. Then you will be able to work with the actual database instead of wasting...