Hello,
I would like to be able to use dia to generate a database schema diagram as documented in Silberschatz et al. and other database textbooks. The schema diagram is a logical representation of the relational model which is in turn derived from the conceptual ER-model design. The main difference among the higher level ER-model and the lower level schema diagram are that in the schema diagram each box represents a physical table which is to be created in the database. Each box contains all of the defining column names which make up the table with the primary key separated from others via a horizontal line. One feature of the schema diagram that the ER-model lacks is the ability to represent foreign key constraints by means of arrows (if this were done in the ER-model then there would be ambiguity as to what an arrow might mean). In the ER-model an arrow points to a relationship to indicate that for each participating entity there is exactly one entity on the other side of the diamond shaped relationship. On the other hand n the schema diagram an arrow points from some column a to another column b in another table indicating that each time a is not null it must appear as a value of b. I think the implementation of schema diagrams would be similar to the UML implementation except for the arrows should be able to go in and out from each row, not from the object itself. Thanks! Neil _______________________________________________ Dia-list mailing list [EMAIL PROTECTED] http://mail.gnome.org/mailman/listinfo/dia-list
