pnewhart (6/23/2011)
Second, how are you demonstrating to allow duplicate NULL values using a filter? Unless some screen prints are missing, I don't see how that's being illustrated. And, unless I'm misunderstanding the functionality of the IGNORE DUP_KEY=ON, this would still only allow one NULL value since it's defined as allowing the inserts to only fail those having duplicate values.
Seconded. If you look closely at the article section on allowing duplicate NULLs, you see a reference to an index AK_UPCode, which is not created in the preceding DDL statements. So something is clearly missing there. Compounding this is the fact that the header for choosing the correct IGNORE DUP_KEY option is not formatted as a header, so the two sections run into each other.