Relational Diagrams

Question

Relational Diagrams

hb21l6

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Points: 1647
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December 5, 2007 at 2:04 am

#103441

just wondering...
why do so many large software development companies not bother with relational Diagrams in their SQL server DBs'?
For instance, there are a number of SQL DB systems ( including Microsofts ) that I'm currently reviewing, and non of them have Relational Diagrams added to them. their table structures are normalised but there is nothing inforcing the fact.
Any ideas?
cheers
Dave

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Greg Charles SSC-Forever Points: 45403 More actions · Answer 1

I can't speak for all companies, but we use a separate CASE tool that has a data repository for logical modeling. We want something that is independent of SQL Server because we have systems on more than just that database platform.

Some of our developers use SQL Server database diagrams for documentation, but they still must maintain their logical designs in the CASE tool.

Greg

Chris Campbell-415954 SSCrazy Points: 2248 More actions · Answer 2

Documentation is superfluous. The code is obvious.

😉

Key DBA SSCertifiable Points: 6029 More actions · Answer 3

In my experience, most companies DO have ERD diagrams/documentation for their database applications, but that information can be considered proprietary information and is not generally given to customers.

Another possibility is that the referential integrity of an application can be completely contained within the application code, and NOT in the database itself. In this type of situation there are literally no Primary Key/Foreign Key relationships within the database.

"Key"
MCITP: DBA, MCSE, MCTS: SQL 2005, OCP

hb21l6 SSCommitted Points: 1647 More actions · Answer 4

yeah, I guess all the constraints can be done within the application.

but to help or even stop end line users from making a mash of the database structure, i would see this as an invaluable tool.

e.g. I have a few databases, and I'd like to tap into them to drag out data for reporting, mabe even make life easier by writing data back to tables for imports, modifications etc. The use of the Diagram is Ideal for looking up references to find tables etc..

oh well... just have to keep spitting nails and working through them slowly

thanks for all your replys...

Dave

Key DBA SSCertifiable Points: 6029 More actions · Answer 5

hb,

With our vendor supported applications that we are not able to get an ERD from, I use Visio Professional 2007 for reverse engineering a database.

I wrote a tutorial in another thread this week at:

Topic: Domains and Schemas

http://www.sqlservercentral.com/Forums/Topic428540-359-2.aspx#bm428845

Best of Luck!

"Key"
MCITP: DBA, MCSE, MCTS: SQL 2005, OCP

Chris Campbell-415954 SSCrazy Points: 2248 More actions · Answer 6

Assuming the tables are already related with foreign keys, you can create a new diagram in SQL Management Studio and simply add all of the tables in the database. The relationships will be automatically drawn in for you.