MadeEasy CBT 2017: Databases - Er Diagram

Question

Please explain how they merged.(Modified)

Comments

Okay, if this is true, then we are saved from considering "=" total participation with "many".

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Why you believe my words ?

Check all gate questions on this topic, just a single search in GO will do that .. then see the diagrams and notations they use !!

i discussed this topic with people , at the end i conclude that no arrow is correct diagram . I did checked gate papers and books too .. no where arrow is used.

check navathe , korth  and settle the answer !!

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Now it is correct .:)

Answer 1

1 table for E₂
1 table for E₃
1 table for (E₁R E₄ )
E1 has total participation with R, it needs no seperate table.
1:1 with only single side total participation we always take 1 table.

so in total 3 tables require here.

Comments

Sir that geeksforgeeks point is wrong we will create separate table only in case of m:n..the answer is 4 only ...

Answer 2

Plz check my answer:
E2{ C,D,A,B }
E3{ E,F, A, B}
E4{ G,H,A,B}

Explanation:
A has total participation in R.
So no need of seprate table.
And R has 1:M relationship with all other tables so no need to maintain seprate table for R.

Correct me if I'm wrong!

Comments

Why not move R in E1. We cannot move E1 to any relation. Correct??