SQL Insert with an incrementing line number

["rick baird" <rick.baird@xxxxxxxxx>]

Hey all,   can this be done with sql?

insert from one file into another -

"from" file has duplicates for order#, no line.
"to" file keyed by order# / line

I want to auto generate the line number in the "to" file, incrementing
by one for each group of orders, resetting on a change in order
numbers.

I looked at NEXT VALUE using sequence objects, but that doesn't seem
to allow the reset on order number breaks.

Thanks in advance,

Rick