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Thread: schema drawings

  1. #1
    Join Date
    Nov 2008

    schema drawings

    Plzz don't laugh at my stupidity. I have no database designing experience. As part of an assignment, I have to design a databasefor a simple order entry application. I have to come up with an ER diagram & a schema drawings for each entity types showing attributes and relationships. I have pretty much done the ER diagram using Ms Visio. But I'm totally lost on the schema drawing. I don't know much about it and how to proceed. How is schema drawing different from an ER diagram? Can anyone shed some light.

  2. #2
    Join Date
    Jan 2007
    I'm not 100% sure, but if I had to guess I'd say that an ER diagram specifies how entities relate to one and other, whereas a schema diagram introduces attributes for the elements.
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  3. #3
    Join Date
    Sep 2002
    An entity diagram is a conceptual data model showing the required entities, relationships and attributes - it is ana anlysis tool. A schema design shows an actual implementation in terms of tables and their foreign keys - it is a design tool. They often look very similar, but there are differences: for example, an entity diagram may show "many to many" relationships, but a schema diagram must show an extra table to implement that relationship.

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