Find minimum number of tables required for converting the following entity…
2019
Find minimum number of tables required for converting the following entity relationship diagram into relational database?
- A.
2
- B.
4
- C.
3
- D.
5
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Correct answer: C
Minimum number of tables required: 3
Explanation:
Table for the first entity (R1): store attributes A and C and the primary key (e.g., R1_id).
Table for the second entity (R2): store attributes X and Y and the primary key (e.g., R2_id). Because the relationship is one-to-many (1 on the R1 side and M on the R2 side), include a foreign key (R1_id) in the R2 table to implement the relationship.
Table for the multivalued attribute B of R1: create a separate relation (e.g., R1_B) with columns (R1_id, B_value). R1_id references R1 and (R1_id, B_value) can form the primary key for this table.
No separate table is needed for the relationship R12 because it is a one-to-many relationship without attributes; a foreign key on the many side suffices.
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