For more fun.....

declare @t1 table (id1 int identity(1,1) primary key, [null] varchar(20))

insert into @t1 values('Null')

insert into @t1 values(null)

insert into @t1 values(default)

declare @t2 table (id2 int identity(11,1) primary key, [null] varchar(20))

insert into @t2 values('Null')

insert into @t2 values(null)

insert into @t2 values(default)

select * from @t1

select * from @t2

select *

from @t1 t1

cross join @t2 t2

where t1.[null] <> t2.[null]

select *

from @t1 t1

cross join @t2 t2

where t1.[null] = t2.[null]