The SQL statements available within the Natural programming language comprise two different syntax sets:

• Common Set
  The Common Set basically corresponds to the standard SQL syntax definitions and is provided for each SQL-compliant database system supported by Natural.

• Extended Set
  The Extended Set, in addition, provides special enhancements to the Common Set to support specific features of the various supported database systems. The supported part of the Extended Set differs with each of these database systems.

The Natural SQL statements documentation mainly describes the Natural SQL Common Set. The statement syntax adheres as far as possible to the syntax described in the relevant literature on SQL; please, refer to this literature for further details. For details on the Natural SQL Extended Set, see the documentation of Natural for Db2.