Self Doubt

Question

Do we need to create a separate table for each of the multivalued attribute irrespective of normal form always?

Comments

I think from 1NF to BCNF, two tables are required :-

In first table, we keep all the multivalued attribute together with the primary key of the original table, and the key of that table is all atribute including primary key and 

In the second table, we keep all the single valued attribute along with primary key of the original table, and the key of that table is the primary key( of the original table) only,

And in 4NF the number of tables depend on the number of multivalued attribute + 1. In this NF we keep all the multivalued attribute seperately with the primary key and the primary key of such tables are that multivalued attribute along with primary key( of the original table), and at last we need one table more to keep all single valued attribute along with primary key. and the key of that table is primary key of the original table itself.

Answer 1

From 1NF to BCNF, two relations are required. One with Primary key and all Single valued attributes and the other with the primary Key and all multi valued attributes.

In 4NF , there are relations for each multi valued attributes.

Ex.   A ia a Entity Set, with key a1 and a2,a3 are single valued attributes and mv1,mv2 are multi valued attributes.

      A( a1,a2,a3,mv1,mv2) 

Converting E-R to Relational Model, 

     A1(a1,a2,a3) and A2(a1,mv1,mv2)

In 4NF

    A1(a1,a2,a3) , A2(a1,mv1) and  A3(a1,mv2)

Comments

Please provide any authentic source

Answer 2

yes .it is mandatory to create a separate table for every  multivalued attribute with primary in the current entity to avoid the heirarchy  in the table.

Answer 3

Yes it is cumpolsary.

Every tablr needs to follow flat hierarchy that is what 1NF says. So if a table is not in 1NF then it cannot be in any other normal form.

CORRECT ME IF I AM WRONG.