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How to draw ER models

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How to draw ER models


ER Models can be drawn using any of several tools.   Among these Dia is a very convenient open source tool which runs on multiple platforms including Linux, Windows and MacOS.
Dia has a number of "sheets" each of which includes diagram objects for different modeling tools, such as UML, ER diagrams, flowcharts, etc.
The ER tool has objects for entities, relationships, attributes (using the oval notation), edges, and so on.  The properties boxes for each of these elements allows you to specify cardinality constraints, total participation, identifying relationship, etc.
To create the ER notation used in the Database System Concepts 6th Ed book, we use the UML class objects instead of ER entity objects in Dia.  Open the properties of the class object and give it a name (entity set name), and add attributes.  Select Visibility  Implementation to remove the + before the attribute name, and select Class Scope to underline an attribute.
Diagrams drawn using Dia can be embedded in other documents by exporting to other formats such as .eps (for Latex) or .jpg (for Word or Open/Libre Office), and including the exported format in the document.

reference: http://www.it.iitb.ac.in/moodle 

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