I am sorry I was corrected by friend of mine that it's Aristotle's idea, not Columbus's (also known as "chicken or the egg") :-)
Thanks Libor 2012/2/10 Libor Jelinek <[email protected]> > Right, John. Because these two tables reference each other with FK > constraints thus one column must allow null. Then it's application logic's > responsibility to ensure that immediately when referenced row from second > table is created it is set in first table (i.e. not leaving it null). > > By the way are there some methodologies in response to this "Columbus's > egg" problem? > > Thank you for your helpful responses! > Libor > > 2012/2/10 John English <[email protected]> > >> On 10/02/2012 02:22, Bergquist, Brett wrote: >> >>> Use >>> >>> alter table business_objects drop constraint fk_created_by;; >>> alter table users drop constraint fk_boid; >>> drop table business objects; >>> drop table users; >>> >>> Basically reverse what you did to create the tables. >>> >>> Brett >>> >> >> As a matter of interest, how would you ever insert data into these two >> tables? Inserting into either one would violate the FK constraint in >> the other, unless the FK allowed nulls -- in which case you do an insert >> with a null key into one table, an insert with non-null into the other, >> and then an update of the first table's FK. Or am I missing something? >> >> ------------------------------**------------------------------** >> ------------ >> John English | My old University of Brighton home page is still here: >> | >> http://www.cem.brighton.ac.uk/**staff/je/<http://www.cem.brighton.ac.uk/staff/je/> >> ------------------------------**------------------------------** >> ------------ >> > >
