if a database is normalised by 3rd normal form

Question

if a database is normalised by 3rd normal form then how many number of tables it should contain in minimum ? how many in minimum if 2NF and 1NF

Answer 1

Hi Vijay,

That is an impossible question to answer, as every single database is different. Theoretically, the mimimum number of tables within any normal form is exactly 1 (Although this of course would be very unlikely and only in rare circumstances).

The point I am trying to make is that there is no minimum or maximum. I suggest that you normalise by applying the rules for each form and then validate your design by using an Entity Model Diagram. If this shows that all your relationships are 1:M than you are normalised.

Here is a link to the NF rules, buy Itzit Ben-Gan's book: Querying T-SQL also has a very good explination.

http://en.wikipedia.org/wiki/Database_normalization

Hope this helps.

Pete

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Peter Carter http://sqlserverdownanddirty.blogspot.com/

Answer 2

Hello,

I dont think it is possible to tell the exact number of tables after normalization. I think you should apply proper rules for normalization follow the link below.

http://www.youtube.com/watch?v=ygfikznRjpw

http://forums.sureshkumar.net/oracle-interview-technical-questions/14602-sql-explain-normalization-examples.html

Answer 3

Hi Vijay,

Please refer links provided by Peter Carter and jigvendtechi, that helps you to clarify NF's and process of normalisation.

In specific to your question, number of tables in a database is mostly based on scope of your project and business attributes. In a normal scenario, real time projects have more than one table in a normalised database that helps to build an application or data warehouse. If normalisation need to be applied while designing DB that is applicable for each table. So, if a database/table is in 3rd normal form then it is already in 1stNF and 2ndNF. Please refer the links below,

http://databases.about.com/od/specificproducts/a/3nf.htm

http://www.agiledata.org/essays/dataNormalization.html

Hope this helps.

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Thanks,
Suresh
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Answer 4

Hi Vijay,

Please provide more detail. Is this an OLAP db or OLTP? When I design an OLTP db i always fully normalize it and then denormalize in situations where performance is enhanced.

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John

http://knowledgy.org