I have a table as folows:

Inv No. Continent Country INV_VAL Town Units_SOLD

1 EUROPE UK 100 LONDON 10
1 EUROPE UK 100 MANCHESTER 3

2 EUROPE UK 500 LIVERPOOL 1
2 EUROPE UK 500 BIRMINGHAM 4


3 ASIA CHINA 300 BEJING 23
3 ASIA CHINA 300 SHANGHAI 12


I want to do a sql select which totals and groups by Continent/Country but ensure
that the INV_VAL column is also totalled correctly.
If I do a sum(Inv_Val) I will get 1200 for Europe instead of 600 (100 + 500)
The Inv_Val already has the total INV_VAL for each invoice.

The resuting table that I need is
Continent Country CTRY_SALES POP_TOTAL
EUROPE UK 600 18
ASIA CHINA 300 35

I have'nt been able to figure out a way to do this with one Sql Seelct command
and am wondering if its possible.
Tia,
Gerard