ER diagram

Question

Is multivalued attribute always create extra table in ER diagram?

Answer 1

No, it creates an extra table only when the number of MVAs are more than 1.
Because when only 1 MVA is present there's no point of creating another table, so that MVA is turned into a SVA and entered in the same table.

Comments

@Vikas Verma In the final relation you've shown in your example, the primary key A is duplicated! How's that possible? Are we going to redefine the primary key attribute?

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Yes, then AC becomes the PK

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if we have more than 1 MVA's then no extra table required for 1NF....but for higher normal forms we require a separate table for each MVA ...right ??

@Vikas Verma

@Somoshree Datta 5

@srestha mam