IT Database Question/ERD Help
All questions relate to the attached project document and ERD that needs corrected. Please answer questions 1 and 2 with 150 words each and references on the information.
1. You will create a Statement of Work. Based upon your understanding, what are your thoughts on ERD and how does this fit into your design process?
2. Read and discuss various relationships associated with ERD (like one-to-many or many-to-many) with suitable examples using ER Assistant.
3. Please see the erd file which is for ER assistant. I need to have the business rules and ERD redone to be correct based on the below feedback. The question 4 is for a statement of work which has example of the draft ERD, so it might be correct.
(Feedback:
| Your ERD had the required five entities with five attributes each, should relationships between the entities, with business rules provided. All the relationships in your diagram showed mandatory participation, while your business rules did not clearly identify if participation was mandatory or optional, and did not fully describe all relationships in both directions. For example, the relationship between customer machines stated: “Many customers can purchase many machines” which does not indicate if a customer must have purchased at least one machine or you can have a customer in the database that has purchased no machines. Likewise the rule does not describe if a machine must have someone purchase it. The rule does imply that a computer can have more than one customer listed is a literal machine, not sure if this is what you intended or not. This could be the case where more than one customer is authorized to request service on a computer, or you could’ve intended that the machine may be owned by only zero or one customer. The ERD had several many to many relationships, that probably should be shown as 1:M relationships, such as the relationships between the service entity and the machine and customer entities. It would appear that one service ticket would refer to one specific machine and be in response to one specific customer request. For example one customer may make zero to many service request but each service ticket will be in response to one and only one customer. For this lab no points were deducted for foreign keys not being listed or identified. For your reference foreign keys always go in the entity on the many side of a 1:M relationship, for example the salesperson_ID would be a foreign key attribute in the sales entity. Your ERD also has several many to many relationships. While it is normal to have many to many relationships when 1st designing a conceptual model, all of these relationships have to be resolved inti one-to-one relationships by use of an associative/bridge/composite entity when developing the final design. The use of associative entities to resolve many to many relationships is already been discussed in class discussion responses and will be discussed further in the coming weeks. ) Question 4:
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