Question

Looking at the following SQL fiddle: http://sqlfiddle.com/#!2/962496/1

How could one select all orders from user [e-mail] with userpk = 2 and reg = 1 but only
the two most recent orders from [e-mail] with userpk = 1 and reg = 0. So the query will show 3 orders for userpk = 2 but only 2 orders (not the earliest order 2012-01-01 from userpk = 1

So the condition would be reg, if reg = 0 then ignore first order

Answer 1

I think this will give you the result that you want:

select *
from users u
left join another a
  on u.userpk = a.uPK
where
(
  u.userpk = 2
  and u.reg = 1
)
or
(
  u.userpk = 1
  and u.reg = 0
  and a.odate not in (select min(odate)
                      from another a1
                      where u.userpk = a1.uPK)
) 

See SQL Fiddle with Demo

A version not specific to single users (if you have more than 2 users):

select *
from users u
left join another a
  on u.userpk = a.uPK
where
(
   u.reg = 1
)
or
(
  u.reg = 0
  and a.odate not in (select min(odate)
                      from another a1
                      where u.userpk = a1.uPK)
) 

See SQL Fiddle with Demo