Originally posted by slimdave
Well strictly speaking this isn't a business rule, it's a denormalization -- what deepa wants to do is store redundant data in a master table.
Interesting! I would say that since the Order Status is a function of other data it could be considered as de-normalisation. HOWEVER the nature of the function is a business rule and as such could change with time (e.g. perhaps later there could be a validation phase in the order closing process?). This example is on the dividing line.

From deepa's second post it sounds as if a trigger may be the only way to start the process (3rd party soft may not give the opportunity to do it any other way - I am faced with that). Is that right deepa? If not, then the quantities should always be modified via a proc, which sets the order status at the same time (as everyone else suggested).

I certainly can't argue with the desirability to keep all the business logic visible. If a process consists of A then B then C, it would not be clever to implement A & C in a block of code with B in a trigger.