--- Michael Glaesemann <[EMAIL PROTECTED]> wrote: > It'd be helpful if you provided links to what you refer to as the > Current style. The only reference for managing temporal data in ANSI > SQL I'm aware of is Snodgrass' "Developing Time-Oriented Database > Applications in SQL"[1]. Date, Darwen, and Lorentzos' "Temporal Data > and the Relational Model"[2] is a more general text on the same > topic, but isn't directly applicable to ANSI SQL.
The "Current style" should actually be called "Current State". There are three temporal models discussed in the Snodgrass book: Current, Sequenced, and Non-Sequenced State Tables. This is described in Chapter 7 sections 1-3. The Current State table only models currently known and historical values of the database. Sequenced and Non-Sequenced can model past/present/future data. The temporal relationship that I am interested in modeling is a temporal parent that is related to a temporal child. I wanted to see if any method exists to support Referential Integrity that can handle Temporal ON UPDATE CASCADE and ON DELETE CASCADE between the parent and child tables. Snodgrass page 127 code fragment 5.20 uses a "CREATE ASSERTION" to maintain RI for CURRENT STATE data between a temporal parent and child. However, I am looking for a method to extend this example to allow ON UPDATE CASCADE and ON DELETE CASCADE, since the CREATE ASSERTION method will only prevent you from from altering the data in a way so as to make it inconsistent between the two tables. > [2](http://www.amazon.com/gp/product/1558608559/) I did purchase the Chris Date book, but I haven't spend any time reading it since its illustrations use Tutorial-D instead of SQL. Regards, Richard Broersma Jr. ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
