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Exercise No. 15: Restaurant Order (dfm)

This E/R-schema is about a restaurant order.

A customer orders a meal. The meal is of a certain type and can be part of the dish of the day. A waiter takes the order and a bill which contains the sum, the tax and the date of the order is attached. The time dimension consists of day, week and month.

 

Figure D.E.41.1 - restaurant order

Please identify the fact of interest and build the attribute tree. In this case we only need the following information of the bill: sum (fact attribute) and date. The tax and the bill itself is not of interest. We only need a classification of the "meal" by "dish of the day". However please bare in mind that the dish of the day is optional. Some attributes cannot be used for aggregation in a meaningful way. Those should be tagged as non-dimension attributes in the fact schema.

Then derive the fact schema from the tree by defining dimensions, fact attributes and hierarchies and build a glossary for the fact attributes.

Please include an additional fact attribute, the numer of customers.

Solution

This exercise is part of a case study: dfm - apa - log

Exercises List