Possible to emulate union all at column level?

Question

The UNION ALL function of Oracle SQL is great for joining two matching results sets into one.
However, is it possible to use a similar approach to do this at column level?
EG:
The following query:
<pre>
select
cods.salesman, sum(cods.net_amount) ordval
from
ifsapp.cust_ord_back_stat cods
where
to_char(cods.statistic_date,'YYYYMMDD') = '20060314'
group by cods.salesman
</pre>
will produce details like:
<pre>
salesman ordval
ARNOTT 100
JONES 15
SMITH 300
</pre>
Showing the balance of orders for each on the 14 March 2006.
Then take the following:
<pre>
select
cods.salesman, sum(cods.net_amount) ordval
from
ifsapp.cust_ord_back_stat cods
where
to_char(cods.statistic_date,'YYYYMMDD') = '20060315'
group by cods.salesman
</pre>
will produce details like:
<pre>
salesman ordval
ARNOTT 120
JONES 5
THOMAS 10
</pre>
Showing the balance of orders for each on the 15 March 2006.
What I want to show is:
<pre>
salesman ordval1 ordval2 diff
ARNOTT 100 120 20
JONES 15 5 10-
SMITH 300 0 300-
THOMAS 0 10 10
</pre>
It seems quite complicated when I think of subqueries etc
Thanks

Answer 1

Apologies on formatting error. Resolved in some respects!
The UNION ALL function of Oracle SQL is great for joining two matching results sets into one.
However, is it possible to use a similar approach to do this at column level?
EG:
The following query:
select
cods.salesman, sum(cods.net_amount) ordval
from
ifsapp.cust_ord_back_stat cods
where
to_char(cods.statistic_date,'YYYYMMDD') = '20060314'
group by cods.salesmanwill produce details like:
salesman ordval
ARNOTT 100
JONES 15
SMITH 300Showing the balance of orders for each on the 14 March 2006.
Then take the following:
select
cods.salesman, sum(cods.net_amount) ordval
from
ifsapp.cust_ord_back_stat cods
where
to_char(cods.statistic_date,'YYYYMMDD') = '20060315'
group by cods.salesmanwill produce details like:
salesman ordval
ARNOTT 120
JONES 5
THOMAS 10Showing the balance of orders for each on the 15 March 2006.
What I want to show is:
salesman ordval1 ordval2 diff
ARNOTT 100 120 20
JONES 15 5 10-
SMITH 300 0 300-
THOMAS 0 10 10It seems quite complicated when I think of subqueries etc
Thanks