About two decades ago, I introduced the concept of transition constraints to show Data Validation in a database is a lot more complex than seeing if a string parameter really is an integer. In October of 2008, I did an article called Constraint Yourself! on how to use DDL constraints to assure data integrity. One of the topics in that piece was a look at state transition constraints via an auxiliary table.
Introduction
Let me give you some introduction, and for some of you flashbacks to your early computer science classes. There is an initial state, flow lines that show