sqlalchemy.sql.schema.Identity

Construct a GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY DDL construct to accompany a :class:`_schema.Column`. See the :class:`.Sequence` documentation for a complete description of most parameters. .. note:: MSSQL supports this construct as the preferred alternative to generate an IDENTITY on a column, but it uses non standard syntax that only support :paramref:`_schema.Identity.start` and :paramref:`_schema.Identity.increment`. All other parameters are ignored. :param always: A boolean, that indicates the type of identity column. If ``False`` is specified, the default, then the user-specified value takes precedence. If ``True`` is specified, a user-specified value is not accepted ( on some backends, like PostgreSQL, OVERRIDING SYSTEM VALUE, or similar, may be specified in an INSERT to override the sequence value). Some backends also have a default value for this parameter, ``None`` can be used to omit rendering this part in the DDL. It will be treated as ``False`` if a backend does not have a default value. :param on_null: Set to ``True`` to specify ON NULL in conjunction with a ``always=False`` identity column. This option is only supported on some backends, like Oracle. :param start: the starting index of the sequence. :param increment: the increment value of the sequence. :param minvalue: the minimum value of the sequence. :param maxvalue: the maximum value of the sequence. :param nominvalue: no minimum value of the sequence. :param nomaxvalue: no maximum value of the sequence. :param cycle: allows the sequence to wrap around when the maxvalue or minvalue has been reached. :param cache: optional integer value; number of future values in the sequence which are calculated in advance. :param order: optional boolean value; if true, renders the ORDER keyword.

Undocumented