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entity-relationshipvisual-paradigm

Visual Paradigm ER diagram adding tables

I am designing an ER diagram to simplify creating tables for my project.I want to add an attribute named phone-number which can hold more than one phone-numbers.How can I do it

Solution

  • Visual Paradigm doesn't really do ER diagrams, it just abuses ER terminology in its schema designer. Dia is a tool that supports both ER diagrams and multivalued attributes.

    To implement multivalued attributes in Visual Paradigm, you need to understand a part of how ER diagrams are translated to physical models. In an ER diagram, we can indicate a customer with a multivalued attribute like so:

    ER diagram

    In a nested / unnormalized tabular model, it would look like this:

    Unnormalized table

    Eliminating repeating groups and choosing a suitable primary key gives us 1st normal form:

    1NF table

    Then dealing with partial dependencies satisifies the rest of the normal forms:

    Normalized table

    From the normalized tables, you can see that to implement a multivalued attribute in a tabular schema design like those produced by Visual Paradigm, you should create a new table to represent the attribute (in ER an attribute is a mapping from an entity set to a value set, hence two columns are here used to represent one attribute). The new table will have a composite primary key consisting of the entity's primary key and the attribute value:

    VP schema