pnewhart (6/23/2011)
First, minor grammatical point: The IGNORE_DUP_KEY option only effects INSERT statements. This should be affects. 🙂
IMO next statement from the article
It is ignored by UPDATE, CREATE INDEX, and ALTER INDEX statements :
is not correct as IGNORE_DUP_KEY does affect UPDATE statements-
try it and you will get error "Cannot insert duplicate key row in object 'dbo.mytbl' with unique index 'nc_index1'."