Classe « Identity »

Constructeur sqlalchemy.Identity.__init__

Signature de la constructeur __init__

def __init__(self, always=False, on_null=None, start=None, increment=None, minvalue=None, maxvalue=None, nominvalue=None, nomaxvalue=None, cycle=None, cache=None, order=None) 

Description

__init__.__doc__

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.