Class Identity

lib/sqlalchemy/sql/schema.py:6070–6223

Defines an identity column, i.e. "GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY" syntax. The :class:`.Identity` construct is an inline construct added to the argument list of a :class:`_schema.Column` object:: from sqlalchemy import Identity Table( "foo",

class Identity(IdentityOptions, FetchedValue, SchemaItem):
    """Defines an identity column, i.e. "GENERATED { ALWAYS | BY DEFAULT }
    AS IDENTITY" syntax.

    The :class:`.Identity` construct is an inline construct added to the
    argument list of a :class:`_schema.Column` object::

        from sqlalchemy import Identity

        Table(
            "foo",
            metadata_obj,
            Column("id", Integer, Identity()),
            Column("description", Text),
        )

    See the linked documentation below for complete details.

    .. versionadded:: 1.4

    .. seealso::

        :ref:`identity_ddl`

    """

    __visit_name__ = "identity_column"

    is_identity = True

    def __init__(
        self,
        always: bool = False,
        on_null: Optional[bool] = None,
        start: Optional[int] = None,
        increment: Optional[int] = None,
        minvalue: Optional[int] = None,
        maxvalue: Optional[int] = None,
        nominvalue: Optional[bool] = None,
        nomaxvalue: Optional[bool] = None,
        cycle: Optional[bool] = None,
        cache: Optional[int] = None,
        order: Optional[bool] = None,
    ) -> None:
        """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: