Find double records

Question

I have following structure:

TradeNo | OrderNo | Buy_Sell | 
1001        2001     Buy
1002        2002     Buy
1001        2001     Sell    

In this particular structure I wanted to find out double records of unique combinations of TradeNo and OrderNo.

I tried the following query:

SELECT t1.tradeno,
       t1.orderno,
       t2.tradeno,
       t2.orderno,
       t1.Buy_sell,
       t2.Buy_sell
FROM tradeFile t1,
     tradeFile t2
WHERE t1.TradeNo=t2.TradeNo
  AND t1.Orderno=t2.orderno

This query , return me two copies of single records. But i wanted to have repeated records finding. Like in above table the first and second record is repeated with unique combination of tradeno and orderno as [1001 and 2001].

Please help me out.

Answer 1

select TradeNo, OrderNo
from TradeFile 
group by TradeNo, OrderNo
having count(*) > 1