[thelist] ERD tool

rudy r937 at interlog.com
Tue Apr 2 21:51:01 CST 2002

> What differentiates it from UML?

what differentiates ERD from UML?

entity-relationship diagramming is a technique for drawing the entities and
the relationships between entities in a database

for an example of an ER diagram, see
http://members.evolt.org/rudy/evolta.gif (caution: not up to date)

i don't know what UML is, but one whitepaper says "UML™ is a
third-generation method for specifying, visualizing, and documenting the
artifacts of an object-oriented system under development. UML represents
the unification of the Booch, Objectory, and OMT methods, and additionally
incorporates ideas from a number of other methodologists, most notably
Wirfs-Brock, Ward, Cunningham, Rubin, Harel, Gamma, Vlissides, Helm,
Johnson, Meyer, Odell, Embley, Coleman, Coad, Yourdon, Shlaer, and Mellor.
UML is the direct and upwardly compatible successor to the Booch,
Objectory, and OMT methods. By unifying these three leading object-oriented
methods, UML provides the basis for a common, stable, and expressive
object-oriented development method."

the following remark may come across as cynical, but i suspect you need
some bigass tools to produce (dare i say understand) UML designs -- the UML
spec itself is a 10 megabyte PDF

i've seen a few UML diagrams, and they look easy enough to understand, but
i wouldn't want to have to create any

ER diagrams, on the other hand, are drop dead simple, and you can do them
on a napkin, with a pencil -- and that is my strong recommendation to
anyone starting out in data modelling, do them by hand before you choose a
diagramming tool

to be fair, though, ER diagramming looks only at the structure of the
stored data, whereas UML covers everything-- business rules, interface
design, code module structure, use case, et cetera

> And yes, Visio does what you are asking for.

does it produce the DDL (the "create table" statements) from the diagram?
neat, but, being a microsoft product, does it produce DDL for any databases
other than sql/server and access?


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