You are expected to create an information system to cater the above information needs of the council. In this assignment, conceptual and logical design phases of the development of that information system have to be carried out. The attributes for various entities have not been purposely described in the case study so that the students are encouraged to further research and list the pertinent attributes in addition to the required identifier for each and every entity in their ERD.
1 Draw an appropriate ER diagram
Use the symbols as prescribed in your course-textbook to draw the ER diagram (ERD) for the above case study.
Your ERD must
show all necessary entities, attributes and relationships
show identifiers/identifying attributes as necessary
show multi-valued attributes, if any
show participation and cardinality
show associative entities, if appropriate
show weak entities, if any
use the notation described in the set text
use consistent and appropriate naming for entities and attributes as specified in the course text book
Some business rules or other aspects of the case study may not be clear to you when you read the case study. If this is the case, then you should either approach your lecturer or tutor for clarification, or you may simply make an assumption and then develop your ERD accordingly. For example, the case study might not mention all relevant participation information (also called minimum cardinalities). If so, you may make an assumption about what the minimum cardinalities might reasonably be, and then show them in your ERD accordingly. You should justify each assumption in terms of the business, for example: it is assumed that each customer must have at least one order because it is assumed that the business does not record customer details until the customer places an order.
To get yourself started, ask yourself, `If I were running this business, what things I need to keep a list of?` Write those things down. For each thing, what information would you need to record about it? How can it be identified? The answers to these questions will help you to develop your ERD.