Database queries usually are quite simple, but sometimes we have to build more complex queries. Let’s have an example We do have a search form where user can select one or many colours of product and one or many sizes.
In many cases we store some additional data in tables, which are helpful for some management tasks. But sometimes those data are problematic, especially if we would lie to have unique data. Lets think about following case. We have table
Sometimes there is a need to connect to other Oracle database from the current database. The case for that issue could be i.e. data migration between databases. So here is the short query to create the ling to other database: