Studierende stehen vor dem LC und blicken lächelnd einer Kollegin mit einer Mappe in der Hand nach.

Exercise No. 43: Flyer (dfm)

This simplified E/R schema describes the "process" of offering flyers.

A student offers a flyer to a person; the flyer is designed by a designer who belongs to a marketing department. The "process" of offering flyers is controlled by an employee of a company which is responsible for the flyers. The time dimension consists of day, week and month.

Figure D.E.19.1 - "process" of offering flyers

Please identify the fact of interest and build the attribute tree. No attributes have to be pruned or grafted, but some of them 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 if there are any.

Please include an additional fact attribute counting the number of flyers.

Solution

Entity FLYER is chosen as the only fact. Its identifier becomes the root of the attribute tree. All other attributes or identifiers become nodes.

Figure D.E.19.2 - The attribute tree

Student, designer, person, company and employee are defined as dimensions, dimension day is introduced as a range of the date attribute. No. of flyers is added as the only fact attribute.

The address of a student cannot be used for aggregation and is therefore tagged as a non-dimension attribute.

Figure D.E.19.3 - The fact schema

no. of flyers = COUNT(FLYER)

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

Exercises List