Entity-Relationship diagrams are widely used in conceptual modeling and data base design. They represent objects (entities) and relationships between objects. They have two types of symbols. Entities and relationships are usually represented as rectangles and diamonds, respectively. Connections between symbols are usually "undirected".

Speaking in terms of graph properties, Entity-Relationship diagrams are undirected graphs.

We suggest to represent Entity-Relationship diagrams with orthogonal drawings, i.e., drawings in which the connections between symbols consist of horizontal and vertical segments only.

The following figures show examples of Entity-Relationship diagrams constructed with GDT.

GAPI tutorial on orthogonal drawings and BLAG tutorial on orthogonal drawings provide a comprehensive guide on how to use GDT to construct these widely used drawings.



An example of system that uses GDT for Entity-Relationship diagrams visualization is Information System Sculptor. Another related system is JBG.

Also, DBdraw is a very interesting tool for automatically visualizing a Microsoft Access database as a relational schema drawing.

Last update : July 31, 2002
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