DB relationships reverse engineered as non-identifying

[Disco Patrick]

Can anyone explain this:

When reverse engineering a DB in Visio Pro 2007, it interprets most of the
relationships as being non-identifying (i.e. they are drawn with a dotted
line) - only two of my relationships are interpreted as identifying. However,
in my head I know that more of these relationships are identifying.

I've tried editing my DB in SQL Server Management Studio to remedy the
problem, e.g. making sure all my foreign key fields do not allow nulls. Visio
still interprets the relationships as non-identifying.

Can anyone list the physical criteria that Visio uses in order to classify
the logical relationship as being either identifying or non-identifying?

 

[Disco Patrick]

I've just had an idea...

I could create a new diagram in Visio, using identifying relationships
between tables, then create a new database from this diagram and examine this
DB to see what is different.

Then again, I have already examined the properties of the relationships in
my current DB, and there does not seem to be a difference between those that
are being interptreted by Visio as identifying, and those that are not.

By the way, I am using the IDEF1X notation, in case you hadn't worked that
out.

 

[Disco Patrick]

....well, I suppose it helps to know the definitions of 'identfying' and
'non-identifying' relationships in the first place.

I had thought that an identifying relationship was one where the child
could not exist without a reference in the parent, however, this is only part
of the story. The child's primary key also has to be partly or fully made up
of the reference in the parent - as explained here:

http://books.google.co.uk/books?id=...X&oi=book_result&resnum=1&ct=result#PPA160,M1