You can define multiple queries with a single SELECT statement by specifying the queries by name.
The WITH modifier defines a named query list from which the SELECT statement can select data. In this way, a query in the WITH modifier is similar to a derived table. Named queries are also referred to as common table expressions (CTEs).
You can only use the WITH modifier with SELECT statements. You cannot use the WITH modifier with other DML statements.
ANSI Compliance
The WITH modifier is ANSI SQL:2011 compliant.
Other SQL dialects support similar non-ANSI standard statements with names such as CONNECT BY PRIOR.