Problem:

(a) Draw an Entity Relationship Diagram for the given case study. Show entities and relationships on the diagram (attributes should not be shown). Cardinality and optionality of relationships should be shown.

(b) The attribute ‘Mileage at last servicing' of the entity E2 Vehicle is not captured in the given system of events. Make the necessary amendment to the event model to correct this anomaly.

(c) The field ‘Total Value of Spare parts used in servicing' was introduced to track expenditure incurred in servicing of vehicles. Is this field a redundancy? Is it justified?

(d) It was also noted that in order to record all costs incurred in the maintenance of a vehicle, it would be necessary to record cost of labour and also the cost of repairs outside normal scheduled servicing tasks. Modify the given event model and the data model to meet this requirement.