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ERD diagrams


In development of system specification and modeling is to analyze the structure of information. In order to create such model for our data structure,there is used the most often conceptual diagrams (conceptual).


In this lesson compounds I will present diagram of ERD entities (entity relationship diagram) which is equivalent to a graphical model of relationship entities ERM (entity relationship model).

ERD helps graphic modelling of data structures and the relationships between them. In this way, you can easily design a structure with ease with all attributes necessary for optimal functioning. If you already have a finished diagram ERD using the CASE system (which also helps in creating diagrams) ,we can often generate a ready-made database.

Diagramming conventions

Below is presented list of alternative diagramming convention: In this lesson ther will be presented Crow's Foot notation which is used in programms such : Toad Data Modeler or Visio.

Basic concepts

To create diagram it should be understood following concepts: Every relation has two ends and each of them has following attributes :


Below is presented simple example of ERD diagram for library. erd [ wróć na górę strony ]