On Thursday 27 October 2005 11:01, Rick Hillegas wrote: > Thanks, Michael. You are correct, Derby, like DB2, finesses this issue > by not allowing nullable columns in unique constraints. I have closed > this bug. > > Cheers, > -Rick > NP,
But Dan's reply is an interesting one. What Sybase did was create a Schrodinger's Cat. (See http://whatis.techtarget.com/definition/0,,sid9_gci341236,00.html for a definition... ;-) This is actually a bug in Sybase. (Note: Bug because by allowing multiple tuples where n-1 of the constraint columns match and the nth column is NULL, the guaranteed uniqueness fails. [Where n = number of columns in the table constraint] ) With respect to constraints in Derby... You really need to consider allowing NULLs in columns that are part of a table constraint. In fact, you should really reconsider how you handle constraints in general. But hey, what do I know? Meow. ;-) -G -- Michael Segel Principal MSCC (312) 952-8175
