UML is a collection of diagrams for very different purposes. E-R diagrams are a specific form of diagrams for showing relationsships of data - which is not directly covered by UML, afaik.
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
ER diagrams are a little like a UML class diagram. You show each entity as a 'box', and draw a 'line' between boxes which are related. You put names inside each 'box' which are called the attributes of the entity/class. If you had to do an ER diagram in a UML model, it would probably be in the class model section. But the term ER diagram usually means a model for a relational database. So the boxes in an ER diagram correspond to tables in a database, where the boxes in a class diagram correspond to Java classes. The lines in an ER diagram correspond to foreign keys, but the lines in a class diagram correspond to inheritance, or the fact that one class contains a reference to another class.
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