Question

I have a table that has redundant data and I’m trying to identify all rows that have duplicate sub-rows (for lack of a better word). By sub-rows I mean considering COL1 and COL2 only.

So let’s say I have something like this:

 COL1   COL2   COL3  ---------------------  aa     111    blah_x  aa     111    blah_j  aa     112    blah_m  ab     111    blah_s  bb     112    blah_d  bb     112    blah_d  cc     112    blah_w  cc     113    blah_p 

I need a SQL query that returns this:

 COL1   COL2   COL3  ---------------------  aa     111    blah_x  aa     111    blah_j  bb     112    blah_d  bb     112    blah_d 

Answer 1

Does this work for you?

select t.* from table t left join ( select col1, col2, count(*) as count from table group by col1, col2 ) c on t.col1=c.col1 and t.col2=c.col2 where c.count > 1