Cardinality Ratio

Question

A project consists of minimum of two employee and maximum of 30 employee. Every employee need not participate into some projects, but if it does then it can be maximum of 4 projects.

Represent the above information in ER diagram, and show the following

1) Which entity in Partial participation and which is in total participation?

2) Represent the cardinality ratio of each entity.

Answer 1

1) project is total participation whereas employee is partial participation..

2) (0,4) for employee and (1,30) for project..

Comments

ok..yes true..!!! .(min,max) is also one way of representing cardinality ratio but in max i thought it will be 0 or 1 like min. thanks:)

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In min-max representation, min should be 2 for project entity type. min-cardinality means minimum number of relationships an entity from entity type project can participate. So, it is $2$ not 1.

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employee  (0:30) project(1:4)

Answer 2

• A. entity employee is partial participation and project is total participation.
• B.  As employee is partial participation then its possible that none of them are forming relationships hence the minimum can be 0 and max is given in question as 4. So, (0,4) is correct for employee. Now, as project is total participation, atleast we would be having 1 relationship so min is 1 and according the question 30 is max. So (1,30). Please correct me if I am wrong.