Need info on the use of constraints

  I 'm currently doing some academical work on constraints in (mainly product model) databases.

  What I'd like to know is to which extend constraints are used in practice for example to modell referentiell integrity.   Are they just used as a debugging tool?   Are constraint checks switched off at run-time to save performace for the end user?
  What are common reactions in case of a constraint violation? Abort the current transaction? Just go on working with inconsistent data, because voilations don't occur very often?

Thanks,
Martin Received on Thu Nov 13 1997 - 00:00:00 CST