Question

A political party would like to store information about different types of ELECTIONs (national, state, municipality, mayor etc.). For each ELECTION, the party would like to store a unique election id, the number of voters, the name of the governing board, and the addresses where people can vote (street, city, state, zip). The party would like to store additional information about some types of elections. For national elections, the party would like to store the possibility of winning (percent chance). For state elections, the party would like to store the names of the winning states. For mayor elections, the party would like to store the name of the candidate.

Draw an EER diagram using supertypes and subtypes to represent the following situation. Be sure to include a subtype discriminator. Except for the subtype discriminator, do not add any attributes that are not explicitly described here. Be sure to check Completeness Constraints and Disjointness Constraints.

Answer 1

Solution:

EER diagram for Elections.

Elections are held in National, state, Municipality and Mayor.

So we apply disjointness to the Elections.

Election Entity has ElectionId which is primary key constraint, Number of votes, Governing body name and Address of the voter

For National election we have an attribute Winning percentage chance

For State election we have an attrbute Winning State

For Mayor election we have an attribute Name of the candidate.