A temporary named result set, known as a common table expression (CTE).
Syntax [ WITH common_table_expression [ ,...n ] ] common_table_expression: expression [( column_name [,...n ])] AS (CTE_query_definition)
This expression is derived from a simple query and defined within the execution scope of a single SELECT, INSERT, UPDATE, or DELETE statement. It must be followed by a single SELECT, INSERT, UPDATE, or DELETE statement that references some or all the same columns.
WITH InventorySales (Product, Sold) AS
SELECT ProductID, COUNT(*) AS Sold
GROUP BY ProductID
SELECT SUM(Sold) AS [number of sales made]
"A chic type, a rough type, an odd type - but never a stereotype" - Jean-Michel Jarre
Equivalent Oracle command:
CREATE TABLE (Temporary)