Question

I’m using this query to find duplicate values in a table:

select col1, 
       count(col1) 
  from table1 
 group by col1 
having count (col1) > 1 
 order by 2 desc;

But also I want to add another column from the same table, like this:

select col1, 
       col2, 
       count(col1) 
  from table1 
 group by col1 
having count (col1) > 1 
 order by 2 desc;

I get an ORA-00979 error with that second query

How can I add another column in my search?

Answer 1

Your query should be

SELECT * FROM (
select col1, 
col2, 
count(col1) over (partition by col1) col1_cnt
from table1 
)
WHERE col1_cnt > 1 
order by 2 desc;