Question is Regarding CTE (Common Table Expresssion)

Hi,

CTE is temporary named result set that you can reference within SELECT, INSERT,UPDATE or DELETE satatements.

A CTE can be used to:

Create a recursive query. For more information, see Recursive Queries Using Common Table Expressions.
Substitute for a view when the general use of a view is not required; that is, you do not have to store the definition in metadata.
Enable grouping by a column that is derived from a scalar subselect, or a function that is either not deterministic or has external access.
Reference the resulting table multiple times in the same statement.