SQL Server select query assistance needed

I'm working on building a query but have a difficult time coming up with the right solutions. Here's what my data looks like...

I have about 10,000 records - bills in my tblBilling.

• Each record has a unique ID number ranging from about 10 - 13000.

• However my primary key is the BillNo which in my records is a 1.

• In case that bill was refunded, another line is added into the tbl but in this case the BillNo is 2.

• Additionally I have another column called AdjType which can either be A, B, C
  • when BillNo is 2, AdjType = B
  • but for normal BillNo 1 - the value is NULL.

So it looks like this...

tblBilling

ID  BillNo  Units  TotalPaid  AdjType
-------------------------------------
10  2       17     230        NULL

So this is a normal Bill where BillNO is 1 - this means that it was a PAID Bill.

Additionally you might have BIllNO2 which is most likely a refund that would look like this....

ID  BillNo  Units  TotalPaid  AdjType
--------------------------------------
10  2       -17    -230       B

So here we are negating Units because its a refund and in this case ADJType = B

Both together if I SELECT * from tblBilling where ID=10 I get this....

ID   BillNo   Units   TotalPaid   AdjType
-----------------------------------------
10     1       17       230       NULL
10     2      -17      -230       B

Now my main goal is to select all records from tblBilling, however I don't want to select any records that have a BillNo 2 associated with them. Basically if a record has BillNO = 1 - that's the record I need. No records that have BillNo=2. Please help!