Topic outline
-
Databases often hold a great amount of data. In order to build a database, we need to understand which entities should hold data and identify the connections that may exist between entities. In this unit, we will learn about the Entity-Relationship model, which will allow us to create a graphical view of the different elements of a database as well as the relationships between them. We will also learn the drawing conventions of the E-R model using a part-to-whole approach, beginning with those conventions used to represent a single entity, and concluding with conventions used to represent all relations in a database. An E-R model is a model of a database's requirements. If we view database development from the perspective of a software life-cycle model, E-R modeling corresponds to requirements analysis. In database terms, this is called conceptual modeling.
Completing this unit should take you approximately 5 hours.
-
-
Students mustMark as done
The lecture explains why entity-relationship (or E-R) models are used, and gives a high-level view of the development process for a database. It describes the database development process as logically parallel to the development process of an application, such as an information system, that uses a database. The development cycle for the application includes requirements analysis, design, and implementation. The development cycle for databases are similar, having a corresponding requirements analysis phase (called the conceptual schema) that is a technical specification of the database requirements. A popular representation of the conceptual schema is an E-R model.
-
-
-
Students mustMark as done
Read chapter 8, which describes an E-R model. An E-R model is conceptually similar to a relational model: E-R entities correspond to relational tables; entity attributes correspond to table columns. An E-R model can easily be translated to a relational model.
-
Students mustMark as done
As you are studying databases, strive to read as many database examples as you can. This resource includes an example E-R model for a SQL movie database.
-
Students mustMark as done
This short description of E-R models demonstrates them from the perspective of application types: OLTP (Online Transaction Processing) and DSS (Decision Support Systems). It also relates E-R notations to other notations.
-
Students mustMark as done
Review these slides, which give an E-R example in the form of an aircraft database. The notes also give a list of rules for interpreting the model.
-
Students mustMark as done
These short videos present an E-R model for a music database from the perspective of the database's requirements and design process.
-
-
-
Students mustMark as done
For some complex applications, an E-R model may not be able to accurately represent the data requirements. To do so, extensions such as specialization, generalization, and inheritance have to be defined. The resulting models are called "enhanced E-R models".
-
Students mustMark as doneThis tutorial goes into some detail on the enhanced E-R modeling concepts that will be helpful when we transition to relational modeling.
-
-
-
Students mustReceive a grade
Take this assessment to see how well you understood this unit.
- This assessment does not count towards your grade. It is just for practice!
- You will see the correct answers when you submit your answers. Use this to help you study for the final exam!
- You can take this assessment as many times as you want, whenever you want.
-