I have a table containing many columns.
What I'm trying to do is find a way I can display duplicates.
My table is info, and whilst it contains many columns, the ones I'm interested in is 'id' and 'shipping_date'. Whilst both shipping_date and id on their own may appear many times, they must not appear more than once together.
select id, shipping_date from T group by id, shipping_date having count(*) > 1;
EDIT: this allows you to find which records are duplicated, not to show duplicated records only once (if that's what you meant).