SQL Join with only first row from joined file

Dear Experts.

I have a problem joining recs in file A with some matching recs from the
same file A.

File A consists of some START and STOP transactions for an item. Having
found a START trans the
join is build to get the STOP trans fir that item in the same file. Both
START and STOP trans have
an activity date, so selecting the STOP trans is build with STOP DATE >=
START DATE.

But here come the problem. Having several sets of START / STOP for an item
leads to getting
more than one matching STOP for a START since other STOP exists with a date
after the START
in question.

But I only want the the STOP matching the START, that means the FIRST
OCCURRENCE from the join.
I need some 'JOIN FIRST on ....'

Does anybody have some nice ideas about this problem ?

Thanks in advance.

Helge