Topic summary
subquery factoring
Extracted from the Wikipedia article Hierarchical and recursive queries in SQL.
Common table expression
Common table expressions are supported by Teradata (starting with version 14), IBM Db2, Informix (starting with version 14.1), Firebird (starting with version 2.1), Microsoft SQL Server (starting with version 2005), Oracle (with recursion since 11g release 2), PostgreSQL (since 8.4), MariaDB (since 10.2), MySQL (since 8.0), SQLite (since 3.8.3), HyperSQL, Informix (since 14.10), Google BigQuery, Sybase (starting with version 9), Vertica, H2 (experimental), and many others. Oracle calls CTEs "subquery factoring".