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Module « sqlalchemy »

Classe « PrimaryKeyConstraint »

Informations générales

Héritage

    builtins.object
        Visitable
builtins.object
    EventTarget
        SchemaEventTarget
            SchemaItem
        builtins.object
            HasConditionalDDL
        builtins.object
            DialectKWArgs
                Constraint
            builtins.object
                ColumnCollectionMixin
                    ColumnCollectionConstraint
                        PrimaryKeyConstraint

Définition

class PrimaryKeyConstraint(ColumnCollectionConstraint):

help(PrimaryKeyConstraint)

A table-level PRIMARY KEY constraint.

The :class:`.PrimaryKeyConstraint` object is present automatically
on any :class:`_schema.Table` object; it is assigned a set of
:class:`_schema.Column` objects corresponding to those marked with
the :paramref:`_schema.Column.primary_key` flag::

    >>> my_table = Table(
    ...     "mytable",
    ...     metadata,
    ...     Column("id", Integer, primary_key=True),
    ...     Column("version_id", Integer, primary_key=True),
    ...     Column("data", String(50)),
    ... )
    >>> my_table.primary_key
    PrimaryKeyConstraint(
        Column('id', Integer(), table=<mytable>,
               primary_key=True, nullable=False),
        Column('version_id', Integer(), table=<mytable>,
               primary_key=True, nullable=False)
    )

The primary key of a :class:`_schema.Table` can also be specified by using
a :class:`.PrimaryKeyConstraint` object explicitly; in this mode of usage,
the "name" of the constraint can also be specified, as well as other
options which may be recognized by dialects::

    my_table = Table(
        "mytable",
        metadata,
        Column("id", Integer),
        Column("version_id", Integer),
        Column("data", String(50)),
        PrimaryKeyConstraint("id", "version_id", name="mytable_pk"),
    )

The two styles of column-specification should generally not be mixed.
An warning is emitted if the columns present in the
:class:`.PrimaryKeyConstraint`
don't match the columns that were marked as ``primary_key=True``, if both
are present; in this case, the columns are taken strictly from the
:class:`.PrimaryKeyConstraint` declaration, and those columns otherwise
marked as ``primary_key=True`` are ignored.  This behavior is intended to
be backwards compatible with previous behavior.

For the use case where specific options are to be specified on the
:class:`.PrimaryKeyConstraint`, but the usual style of using
``primary_key=True`` flags is still desirable, an empty
:class:`.PrimaryKeyConstraint` may be specified, which will take on the
primary key column collection from the :class:`_schema.Table` based on the
flags::

    my_table = Table(
        "mytable",
        metadata,
        Column("id", Integer, primary_key=True),
        Column("version_id", Integer, primary_key=True),
        Column("data", String(50)),
        PrimaryKeyConstraint(name="mytable_pk", mssql_clustered=True),
    )

Constructeur(s)

Signature du constructeur	Description
__init__(self, *columns: '_DDLColumnArgument', name: 'Optional[str]' = None, deferrable: 'Optional[bool]' = None, initially: 'Optional[str]' = None, info: 'Optional[_InfoType]' = None, _implicit_generated: 'bool' = False, **dialect_kw: 'Any') -> 'None'

Liste des opérateurs

Opérateurs hérités de la classe ColumnCollectionConstraint

__contains__

Liste des opérateurs

Opérateurs hérités de la classe object

__eq__, __ge__, __gt__, __le__, __lt__, __ne__

Méthodes héritées de la classe ColumnCollectionConstraint

__iter__, __len__, __subclasshook__, contains_column, copy

Méthodes héritées de la classe SchemaItem

__repr__

Méthodes héritées de la classe Visitable

__class_getitem__, __init_subclass__

Méthodes héritées de la classe HasConditionalDDL

ddl_if

Méthodes héritées de la classe DialectKWArgs

argument_for

Méthodes héritées de la classe object

__delattr__, __dir__, __format__, __getattribute__, __getstate__, __hash__, __reduce__, __reduce_ex__, __setattr__, __sizeof__, __str__

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