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Sequencediagram org examples12/11/2023 ![]() Now we have a Main method, and ReadNumber method. Let’s take our Book and Person, but now with more than one relationship: Just like in class diagrams, ER diagrams can also used to describe cardinalities. The relation can also be drawn other way around, but let’s keep this simple. This example is now read from left to right, as in “Person writes a book”. The relationship between the two is still the same, but in ER, the relationships are written as verbs. Now we can see, that our “author” has changed to “writes”. In our diagram, the relationship between entities is in the middle, marked with a diamond shape. The entity name, as well as the attributes, are written as singular nouns. The Entity has two Attributes, described with elliptical shapes. In our diagram, we have an Entity called Person, described with a rectungular shape. Starting off small, let us have the class “Person” as an ER diagram. Let us use one of our previous class diagrams as an example, and change that into an ER diagram. According to their name, the ER diagrams DO NOT describe the inner functions of entities, but merely the relations between them. They are used for example conceptualizing a software, before actually implementing said software. In software engineering, the ER model can be used to describe for example business models, but also data models or software structures.ĮR models are not part of the UML standard, but are still quite often used. A basic ER model is composed of entity types and specifies relationships between those entities. ![]()
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