Richard Gibbins (1/27/2010)
The whole point of null is that the value is undefined so comparing a value and saying they are equal if both are null is not valid.
The currently defined behaviour in SQL Server depends on the setting of ANSI_NULLS - see http://msdn.microsoft.com/en-us/library/ms188048.aspx. Thankfully, we are moving to a point where the statement quoted above will be true some day.
Paul White
SQLPerformance.com
SQLkiwi blog
@SQL_Kiwi