Classe « Sequence »

Constructeur sqlalchemy.Sequence.__init__

Signature de la constructeur __init__

def __init__(self, name, start=None, increment=None, minvalue=None, maxvalue=None, nominvalue=None, nomaxvalue=None, cycle=None, schema=None, cache=None, order=None, data_type=None, optional=False, quote=None, metadata=None, quote_schema=None, for_update=False) 

Description

__init__.__doc__

Construct a :class:`.Sequence` object.

        :param name: the name of the sequence.

        :param start: the starting index of the sequence.  This value is
         used when the CREATE SEQUENCE command is emitted to the database
         as the value of the "START WITH" clause.   If ``None``, the
         clause is omitted, which on most platforms indicates a starting
         value of 1.
        :param increment: the increment value of the sequence.  This
         value is used when the CREATE SEQUENCE command is emitted to
         the database as the value of the "INCREMENT BY" clause.  If ``None``,
         the clause is omitted, which on most platforms indicates an
         increment of 1.
        :param minvalue: the minimum value of the sequence.  This
         value is used when the CREATE SEQUENCE command is emitted to
         the database as the value of the "MINVALUE" clause.  If ``None``,
         the clause is omitted, which on most platforms indicates a
         minvalue of 1 and -2^63-1 for ascending and descending sequences,
         respectively.

         .. versionadded:: 1.0.7

        :param maxvalue: the maximum value of the sequence.  This
         value is used when the CREATE SEQUENCE command is emitted to
         the database as the value of the "MAXVALUE" clause.  If ``None``,
         the clause is omitted, which on most platforms indicates a
         maxvalue of 2^63-1 and -1 for ascending and descending sequences,
         respectively.

         .. versionadded:: 1.0.7

        :param nominvalue: no minimum value of the sequence.  This
         value is used when the CREATE SEQUENCE command is emitted to
         the database as the value of the "NO MINVALUE" clause.  If ``None``,
         the clause is omitted, which on most platforms indicates a
         minvalue of 1 and -2^63-1 for ascending and descending sequences,
         respectively.

         .. versionadded:: 1.0.7

        :param nomaxvalue: no maximum value of the sequence.  This
         value is used when the CREATE SEQUENCE command is emitted to
         the database as the value of the "NO MAXVALUE" clause.  If ``None``,
         the clause is omitted, which on most platforms indicates a
         maxvalue of 2^63-1 and -1 for ascending and descending sequences,
         respectively.

         .. versionadded:: 1.0.7

        :param cycle: allows the sequence to wrap around when the maxvalue
         or minvalue has been reached by an ascending or descending sequence
         respectively.  This value is used when the CREATE SEQUENCE command
         is emitted to the database as the "CYCLE" clause.  If the limit is
         reached, the next number generated will be the minvalue or maxvalue,
         respectively.  If cycle=False (the default) any calls to nextval
         after the sequence has reached its maximum value will return an
         error.

         .. versionadded:: 1.0.7

        :param schema: optional schema name for the sequence, if located
         in a schema other than the default.  The rules for selecting the
         schema name when a :class:`_schema.MetaData`
         is also present are the same
         as that of :paramref:`_schema.Table.schema`.

        :param cache: optional integer value; number of future values in the
         sequence which are calculated in advance.  Renders the CACHE keyword
         understood by Oracle and PostgreSQL.

         .. versionadded:: 1.1.12

        :param order: optional boolean value; if ``True``, renders the
         ORDER keyword, understood by Oracle, indicating the sequence is
         definitively ordered.   May be necessary to provide deterministic
         ordering using Oracle RAC.

         .. versionadded:: 1.1.12

        :param data_type: The type to be returned by the sequence, for
         dialects that allow us to choose between INTEGER, BIGINT, etc.
         (e.g., mssql).

         .. versionadded:: 1.4.0

        :param optional: boolean value, when ``True``, indicates that this
         :class:`.Sequence` object only needs to be explicitly generated
         on backends that don't provide another way to generate primary
         key identifiers.  Currently, it essentially means, "don't create
         this sequence on the PostgreSQL backend, where the SERIAL keyword
         creates a sequence for us automatically".
        :param quote: boolean value, when ``True`` or ``False``, explicitly
         forces quoting of the :paramref:`_schema.Sequence.name` on or off.
         When left at its default of ``None``, normal quoting rules based
         on casing and reserved words take place.
        :param quote_schema: Set the quoting preferences for the ``schema``
         name.

        :param metadata: optional :class:`_schema.MetaData` object which this
         :class:`.Sequence` will be associated with.  A :class:`.Sequence`
         that is associated with a :class:`_schema.MetaData`
         gains the following
         capabilities:

         * The :class:`.Sequence` will inherit the
           :paramref:`_schema.MetaData.schema`
           parameter specified to the target :class:`_schema.MetaData`, which
           affects the production of CREATE / DROP DDL, if any.

         * The :meth:`.Sequence.create` and :meth:`.Sequence.drop` methods
           automatically use the engine bound to the :class:`_schema.MetaData`
           object, if any.

         * The :meth:`_schema.MetaData.create_all` and
           :meth:`_schema.MetaData.drop_all`
           methods will emit CREATE / DROP for this :class:`.Sequence`,
           even if the :class:`.Sequence` is not associated with any
           :class:`_schema.Table` / :class:`_schema.Column`
           that's a member of this
           :class:`_schema.MetaData`.

         The above behaviors can only occur if the :class:`.Sequence` is
         explicitly associated with the :class:`_schema.MetaData`
         via this parameter.

         .. seealso::

            :ref:`sequence_metadata` - full discussion of the
            :paramref:`.Sequence.metadata` parameter.

        :param for_update: Indicates this :class:`.Sequence`, when associated
         with a :class:`_schema.Column`,
         should be invoked for UPDATE statements
         on that column's table, rather than for INSERT statements, when
         no value is otherwise present for that column in the statement.