On 5/29/07, David Tangye <[EMAIL PROTECTED]> wrote: > That seems to be going in the right direction. It would be nice to > have comments on the columns, but the usage of most can be guessed by > good naming. > > Two questions: > 1. Column "entity_class (not null)" in TABLE "entity": is it > something like "current_default/primary_class", whatever that might > be?
Ok. Think of an entity as a "legal person" (corporate or natural) and a contact as a "natural person." The idea is that each entity has one primary class and may have many auxiliary classes. So an entity can be a customer, a vendor, etc. all at once. > > 2. The term and term fragment "class" (assuming it means "our way of > classifying the entities") might be better understood using the term > and term fragment "role". Term fragments class/group/type are all > shallow terms in entity/logical modelling. What we want to know is WHY > we are classifying/grouping/typifying an entity. Think of possible classes as any of (lead, customer, vendor, member, any that might be added later). I tend to think of "role" as being somethign that defines what something defines what something does, while this allows us to essentially categorize legal persons with whome we do business or intend to do such business. > The reason for making > the classification/grouping/typification is usually the best term to > use. In this case we are classifying based on the role the entity has. > Therefore "role" is a better choice than "class" in this model. Before > you go further I would rename "class" to "role" everywhere that it > occurs in this physical model. Wouldn't that get confusing when we implement "role-level security" for users? > > Later you might also classify entities in another way, eg based on > whether they are current or not, alive or dead perhaps. > > (Rules for classification can be implicit in events/transactions that > change the state of an entity(in logical modelling) from oe state to > another, and be explicitly or redundantly recorded in both the logical > and physical models as classifications.) I would suggest that both role and class are both well understood English terms relating to divisions based on the nature of the interaction. Since Role is intended to be used elsewhere, I would suggest we stick with class. Best Wishes, Chris Travers ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Ledger-smb-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/ledger-smb-devel
