How to display only the duplicate records

Question

Hi friends,
I have a query that provides me with a set of data,which has some duplicate rows. I require to display only the duplicates.
This is the result I have:
card_no cust_no address paymnt_mode
1234 A123 XYZ CQ
1234 A234 nmb CC
9876 B123 mnnjn cc
5678 A123 XYZ CQ
5678 A123 XYZ CQ
7876 Mk89 mku CC
From the above ,
I require to display something like this:(Duplicates based on card number alone)
card_no cust_no address paymnt_mode
1234 A123 XYZ CQ
1234 A234 nmb CC
5678 A123 XYZ CQ
5678 A123 XYZ CQ
Please share some ideas,
Thanks a lot

Answer 1

with data as
  select 1234 as card_no, 'A123' as cust_no, 'XYZ' as address, 'CQ' as paymnt_mode from dual union all
  select 1234, 'A234', 'nmb', 'CC' from dual union all
  select 9876, 'B123', 'mnnjn', 'cc' from dual union all
  select 5678, 'A123', 'XYZ', 'CQ' from dual union all
  select 5678, 'A123', 'XYZ', 'CQ' from dual union all
  select 7876, 'Mk89', 'mku', 'CC' from dual
select card_no, cust_no, address, paymnt_mode
from
    select card_no, cust_no, address, paymnt_mode, count(*) over (partition by card_no) as cardinality
    from data
where cardinality > 1;
CARD_NO                CUST_NO ADDRESS PAYMNT_MODE
1234                   A123    XYZ     CQ         
1234                   A234    nmb     CC         
5678                   A123    XYZ     CQ         
5678                   A123    XYZ     CQ          Change the column list in the partition by clause if you want to check over other columns as well.