#ER_diagrams #self_doubt

Question

If A,B and C have 30,50,70 tuples respectively.Then maximum no of triples possible of entities <A,B,C> that could be in the relation R?

Answer 1

I think we can combine relation table towards  A in case of minimum .

But here we are talking about maximum so (30*1)*70 entries .

Comments

because its a many to one relation as shown in E R Diagram . And between A and C its many to many relationship

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For maximum tuples in R-

As A and C is having "many" cardinality with R i.e 1 tuple of A can be related to at most all the tuples in C(70) and 1 tuple in C can be related with at most all the tuples in A(30) i.e maximum tuples in A and C = 30*70

Now jointly A and C is also having "many to one" relation with B i.e many tuples of AC are related to exactly one tuple(any) in B.Hence tuples in B cannot be repeated when mapped with AC.

So total maximum tuples possible now are the same as that of AC i.e 30*70

Hope it is clear!

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Wow. That makes a lot of sense.
Thank you.