Relational Diagrams

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Relational Diagrams

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hb21l6

Posted Wednesday, December 05, 2007 2:04 AM

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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

Post #429673

Greg Charles

Posted Wednesday, December 05, 2007 9:15 AM

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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

Greg

Post #429831

Chris Campbell-415954

Posted Thursday, December 06, 2007 7:20 AM

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Documentation is superfluous. The code is obvious.

;)

Post #430177

Key DBA

Posted Thursday, December 06, 2007 7:27 AM

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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

Post #430180

hb21l6

Posted Thursday, December 06, 2007 9:28 AM

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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

Post #430280

Key DBA

Posted Thursday, December 06, 2007 10:56 AM

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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

Post #430325

Chris Campbell-415954

Posted Thursday, December 06, 2007 11:24 AM

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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.

Post #430349

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