sqlalchemy.sql.schema.ForeignKey

Construct a column-level FOREIGN KEY. The :class:`_schema.ForeignKey` object when constructed generates a :class:`_schema.ForeignKeyConstraint` which is associated with the parent :class:`_schema.Table` object's collection of constraints. :param column: A single target column for the key relationship. A :class:`_schema.Column` object or a column name as a string: ``tablename.columnkey`` or ``schema.tablename.columnkey``. ``columnkey`` is the ``key`` which has been assigned to the column (defaults to the column name itself), unless ``link_to_name`` is ``True`` in which case the rendered name of the column is used. :param name: Optional string. An in-database name for the key if `constraint` is not provided. :param onupdate: Optional string. If set, emit ON UPDATE <value> when issuing DDL for this constraint. Typical values include CASCADE, DELETE and RESTRICT. :param ondelete: Optional string. If set, emit ON DELETE <value> when issuing DDL for this constraint. Typical values include CASCADE, DELETE and RESTRICT. :param deferrable: Optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when issuing DDL for this constraint. :param initially: Optional string. If set, emit INITIALLY <value> when issuing DDL for this constraint. :param link_to_name: if True, the string name given in ``column`` is the rendered name of the referenced column, not its locally assigned ``key``. :param use_alter: passed to the underlying :class:`_schema.ForeignKeyConstraint` to indicate the constraint should be generated/dropped externally from the CREATE TABLE/ DROP TABLE statement. See :paramref:`_schema.ForeignKeyConstraint.use_alter` for further description. .. seealso:: :paramref:`_schema.ForeignKeyConstraint.use_alter` :ref:`use_alter` :param match: Optional string. If set, emit MATCH <value> when issuing DDL for this constraint. Typical values include SIMPLE, PARTIAL and FULL. :param info: Optional data dictionary which will be populated into the :attr:`.SchemaItem.info` attribute of this object. .. versionadded:: 1.0.0 :param comment: Optional string that will render an SQL comment on foreign key constraint creation. .. versionadded:: 2.0 :param \**dialect_kw: Additional keyword arguments are dialect specific, and passed in the form ``<dialectname>_<argname>``. The arguments are ultimately handled by a corresponding :class:`_schema.ForeignKeyConstraint`. See the documentation regarding an individual dialect at :ref:`dialect_toplevel` for detail on documented arguments. .. versionadded:: 0.9.2

Undocumented

Undocumented

Return the :class:`_schema.Column` in the given :class:`_schema.Table` (or any :class:`.FromClause`) referenced by this :class:`_schema.ForeignKey`. Returns None if this :class:`_schema.ForeignKey` does not reference the given :class:`_schema.Table`.

Return True if the given :class:`_schema.Table` is referenced by this :class:`_schema.ForeignKey`.