Er diagram to table Doubt

Question

Please clarify me:-

In one to one with total participation on any side we can simply merge everything to one table because it's one to one so no redundancy will be there,but in case of many to one or many to many with total participation on any end we can't merge everything into one because since one entity can be related to many instance of other entity there will be redundancy. Which will satisfy 1nf as redundancy can be there but not 2nf because it will cause partial dependency to arrive so we break it down hence in many to one :- 2 tables because the relation can be merged with many side.

But in many to many with any sort of cardinality there would always be 3 tables because here we still cant merge R with any of the entities isn't it?

 

Am I right?

Comments

Yes ,for 2nf three table are required

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I am little confused. Say in a question its asked to find out the minimum number of tables to represent ER Diagram and nothing says about whether in 1nf or 2nf then what assumption should i take.

I suppose it should be in 1nf cuz its the minimum requirment to be followed. Now in this Question : https://gateoverflow.in/390/gate2008-82

Cant we merge M and P together because there is a total participation on M side the merged relation can have null values but the primary key(i.e. the key attribute M which is M1) won't hence it satisfies 1nf.Likewise then Entire this new Relation can be merged with N with the same logic. Then why is the answer 3.

If we think by another logic which is :- 

Since M is on total participation side. The Relation R1 will have the Key(M1,P1),M1 being the Primary key  and we can merge the relation with M hence total 2 tables. i.e. (M+R1) and P, likewise we can merge N with R2 but first the primary key of P1 will be inherited by the Relation N. Hence total 3 tables

Now which way to think and why ?

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@Na462 @Prateek Raghuvanshi I am still confused after reading whole discussion you guys had!

How to handle one-to-one relationship with total participation in relationship?

How to handle Many-to-one relationship with total participation?

How to handle many-to-many with total participation in relationship?