delete from tbl_talbe

where (col1,col2,col3) in

(select col1,col2,col3

from tbl_table

group by col1,col2,col3

having count(*)>1)

and rowid not in

(

select max(rowid)

from tbl_table

group by col1,col2,col3

having count(*) >1

)

?

?