SQL charge reversal data - sql

Question

I'm extracting financial information, but ran into charge reversal information. Basically if someone was charged for a service there would be a column with that charge. If the charge was later reversed there would be another row with the exact same data, but with a charge reversal flag on it. I want to only get charges that are were not reversed at all.
Below is an example of what i mean and need. As you can see the RVSLInd column has a 1 if the charge is a reversal. The 0 represents an initial charge
I couldn't do: select * from from table where rvslInd = 0. because this would get rid of the reversal row only.
RvslInd|ExtPriceAmt
-------| ----------|
0 | 155.70 |
0 | 1.50 |
0 | 239.00 |
0 | 1111.00 |
1 | -1111.00 |
0 | 217.00 |
0 | 1491.00 |
1 | -1491.00 |
0 | 388.00 |
0 | 72.00 |
This is what I want to be able to get back:
RvslInd|ExtPriceAmt
-------| ----------|
0 | 155.70 |
0 | 1.50 |
0 | 239.00 |
0 | 217.00 |
0 | 388.00 |
0 | 72.00 |
this would be my new table with a customer column added:
CustomerID|RvslInd|ExtPriceAmt
----------|-------| ----------|
1 | 0 | 155.70 |
1 | 0 | 1.50 |
1 | 0 | 239.00 |
2 | 0 | 217.00 |
2 | 0 | 388.00 |
2 | 0 | 72.00 |

Answer 1

Given your data, you cannot reliably do what you want. For the data you have shown, you could do:
select ExtPriceAmt
from t
where RvslInd = 0 and
not exists (select 1 from t t2 where t2.ExtPriceAmt = - t.ExtPriceAmt and t2.RvslInd = 1);
The problem is when the price is repeated. That gets in the way.
That said, all is not hopeless. You can get a list of the prices along with the number of non-reversed times:
select ExtPriceAmt,
sum(case when RvslInd = 0 then 1 when RvslInd = 1 then -1 end) as non_reversed_count
from t
group by ExtPriceAmt
having sum(case when RvslInd = 0 then 1 when RvslInd = 1 then -1 end) > 0;