2 Selects ---> 1 Self Join

Hi, I asked this in ACCESS section but here says ask an expert...
if its a duplicate post please delete it(here is more explained) otherwise here is my question:

Before going further whats better 2 Selects in a query or 1 Self Join (In terms of efficiency)?

If its better 1 self join rather than 2 Selects... here we go:

Database: Access 2000

If i have a table like this:

SN VN GV LD LV (Ignore "..")
a..a1..a2..1..0
a..a2..a3..2..0
X.. Y.. Z ..1..2
X.. Y.. Z ..2..2
x.. b.. c ..1..2
b.. b.. b ..2..2
---------------

Conditions: SN = 'X' AND VN = 'Y' AND GV= 'Z' AND MIN(LD)

My query should show just this: (I dont need to select LV)

SN VN GV LD
X Y Z 1

Right now my query shows:
SN VN GV LD
X Y Z 1

So it works fine. But im looking to be more efficient thats why i thought in a Self join.

This is my query:

SELECT l.SN, l.VN, l.GN, l.LD
FROM l
WHERE (((l.SN)='X') AND ((l.VN)='Y') AND ((l.GN)='Z') AND ((l.LD)<=(Select MIN(l2.LD) from l l2 where ((l2.SN)='X') AND ((l2.VN)='Y') AND ((l2.GN)='Z') )));

I tried to do the self join of this query but didnt do it right :/
So any advice/help will be appreciated.

Thanks in advance

Regards.

FIXED, i dont need the answer... i found the solution was quite simple :/ just with one select and some group by fixed the problem.