Common table expression
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A Common Table Expression (in SQL) is a temporary named result set, derived from a simple query and defined within the execution scope of a SELECT, INSERT, UPDATE, or DELETE statement.
CTE can be thought of as an alternatives to derived tables (subquery), views, and inline user-defined functions.
Common table expressions
Common table expressions are supported by DB2, Firebird [1], Microsoft SQL Server, Oracle and PostgreSQL. Syntax:
WITH [RECURSIVE] with_query [, ...] SELECT...
with_query looks like
with_query_name [ (column_name [,...]) ] AS (SELECT ...)
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