Since the referential integrity was imposed between the tabular variables CITIES and STORES we need to insert the tuples of CITIES before we can insert the tuples of STORES. Otherwise, the cities mentioned in the values of STORES can not reference a city in a value of CITIES and the insertion in STORES will be rejected.
The presence of on delete cascade means that if a row is removed from a table CITIES that the rows corresponding to that city are also removed. For example, if the company closes its business in Hartford and we execute
delete from CITIES where