The Data Model Resource Book, Volume 3: Universal Patterns for Data Modeling

Silverston c06.tex V2 - 11/21/2008 3:09am Page 240

240 Chapter 6 ■ Status: The States of Data

Two patterns at the end of this chapter, the ‘‘Status Category Pattern’’ and

the ‘‘Status Type with Multi Rollup and Rules Pattern,’’ are provided as a

way to e nhance the level 2, level 3, or level 4 patterns. These patterns e nhance

the status pattern by bringing in patterns from chapter 5 (on classifications)

and chapter 4 (on recursions). The ‘‘Status Category Pattern’’ supports the

need to classify statuses into various sets and can help when an entity has

more than one set of statuses. For example, an ORDER may have one set of

statuses for order proce ssing (‘‘Received,’’ ‘‘Entered,’’ and ‘‘Confirmed’’) and

another set of statuses for scheduling (‘‘On Schedule,’’ ‘‘Behind Schedule,’’ and

‘‘Overdue’’). The ‘‘Status Type with Multi Rollup and Rules Pattern’’ supports

the need to maintain rules about how statuses can (or can’t) be related to each

other. In other words, you may want to maintain that you cannot have an

order that is ‘‘Entered’’ before you have ‘‘Received’’ that order.

NOTE

The same concept that is used in the ‘‘Status Category Pattern’’ and the

‘‘Status Type with Multi Rollup and Rules Pattern,’’ namely of using other patterns

to enhance a pattern and, in this case, specifically adding flexible self-associations

(recursions) and classifications, may be used as a technique to enhance other