Common_Table_Expression :

This is nothing but a variable used to store the result set temporarily
which is derived from the another table and defined within the execution scope
of the query used to build this CTE.

Syntax for CTE:

WITH Common_Table_Expression (Column1, ....n)
As
( CTE Query Definition )

Example :

WITH CTE_Project (Project_ID)
As
(Select ProjectID From Project)


Select * From CTE_Project