Show all the catalog information and their respective levels numbers!
select * from catalogs as t1 join catalog_structure as t2 on t1.catalog_id = t2.catalog_id
Show me only those with a level number greater than five.
select * from catalogs as t1 join catalog_structure as t2 on t1.catalog_id = t2.catalog_id where catalog_level_number > 5
Show me just the names of these catalogs?
select t1.catalog_name from catalogs as t1 join catalog_structure as t2 on t1.catalog_id = t2.catalog_id where catalog_level_number > 5
Also show their publication dates.
select t1.catalog_name, t1.date_of_publication from catalogs as t1 join catalog_structure as t2 on t1.catalog_id = t2.catalog_id where catalog_level_number > 5