Interesting SQL

select * from #t1

can also be written as....

select * from #t1 t1 left join #t2 t2
on 1 = 2

While:
select * from #t1 t1 left join #t2 t2
on 1 = 1
... is really a cross join.

This is acceptable:

select * from
(select 1 a, 2 b, 3 c) t1
full outer join
(select 2 a, 4 b, 5 c) t2
on t1.a = t2.a

Perhaps not very useful, but interesting to know nonetheless as they are available. And, I really do like (T-SQL's new) MERGE statement.