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I am given a case study of Event Management to develop an ER model and based on it its normalization forms and relational schema. Now i have developed my ER Model based on the SRS that i have developed. Now the question that i am having is when i converted my ER diagram to the relational schema i got my tables already normalized. Because of the ER diagram i had nothing to do more in normalization process so i got confused.

Now the question arose in my mind is whether or not it is desirable situation? I mean when i am getting my all the relations normalized from the ER diagram itself then why do i need to do normalization at all?

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Note "normalized" means in 1NF and "fully normalized" means in 5NF or 6NF. – onedaywhen Oct 19 '11 at 14:31
I talking about all kind of normalization. If we get the database already in 5NF from erd then why do we need to think of normalization ? – ankurtr Oct 19 '11 at 14:53

If your tables are already in 5NF then you don't need to think much more about further normalization.

Note however that the principle of full normalization (POFN) is no panacea. There may remain non-obvious update anomalies.

Database constraints will need to be applied. In my experience, designers who start with an ER diagram are great at implementing primary keys and foreign keys but other constraints can be easily overlooked. Other design approaches may result in better constraints e.g. I have a little experience of object role modelling which seemed to work well.

Further normalization should only be considered in conjunction with constraints because 6NF often makes constraints more difficult to implement using today's industrial-strength technologies e.g. none support Standard SQL's CREATE ASSERTION nor CHECK constraints that may include a subquery.

Also consider the principle of orthogonal design (POOD).

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I much prefer ORM to ER modelling because what you get is more complete. See LinkedIn group of you can – gbn Dec 9 '11 at 12:37
@gbn: My membership is now pending. Do you use ORM much? – onedaywhen Dec 9 '11 at 13:25
Not as much as I would like. Wrong role currently. I'm doing some in my spare time but I lack a practical "mission" – gbn Dec 9 '11 at 13:27

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