What were the dates of the latest revisions?
select date_of_latest_revision from catalogs
Which of these appear more than once?
select date_of_latest_revision from catalogs group by date_of_latest_revision having count ( * ) > 1
What catalogs were done on these dates?
select catalog_name from catalogs where date_of_latest_revision in ( select date_of_latest_revision from catalogs group by date_of_latest_revision having count ( * ) > 1 )
Great, can you show me the dates these catalogs were revised again?
select catalog_name, date_of_latest_revision from catalogs where date_of_latest_revision in ( select date_of_latest_revision from catalogs group by date_of_latest_revision having count ( * ) > 1 )
Can you show me what dates appear more than once again?
select date_of_latest_revision from catalogs group by date_of_latest_revision having count ( * ) > 1