sqlalchemy.sql.ddl.ExecutableDDLElement

Execute the DDL as a ddl_listener.

Return a copy of this :class:`_schema.ExecutableDDLElement` which will include the given target. This essentially applies the given item to the ``.target`` attribute of the returned :class:`_schema.ExecutableDDLElement` object. This target is then usable by event handlers and compilation routines in order to provide services such as tokenization of a DDL string in terms of a particular :class:`_schema.Table`. When a :class:`_schema.ExecutableDDLElement` object is established as an event handler for the :meth:`_events.DDLEvents.before_create` or :meth:`_events.DDLEvents.after_create` events, and the event then occurs for a given target such as a :class:`_schema.Constraint` or :class:`_schema.Table`, that target is established with a copy of the :class:`_schema.ExecutableDDLElement` object using this method, which then proceeds to the :meth:`_schema.ExecutableDDLElement.execute` method in order to invoke the actual DDL instruction. :param target: a :class:`_schema.SchemaItem` that will be the subject of a DDL operation. :return: a copy of this :class:`_schema.ExecutableDDLElement` with the ``.target`` attribute assigned to the given :class:`_schema.SchemaItem`. .. seealso:: :class:`_schema.DDL` - uses tokenization against the "target" when processing the DDL string.

Return a callable that will execute this :class:`_ddl.ExecutableDDLElement` conditionally within an event handler. Used to provide a wrapper for event listening:: event.listen( metadata, 'before_create', DDL("my_ddl").execute_if(dialect='postgresql') ) :param dialect: May be a string or tuple of strings. If a string, it will be compared to the name of the executing database dialect:: DDL('something').execute_if(dialect='postgresql') If a tuple, specifies multiple dialect names:: DDL('something').execute_if(dialect=('postgresql', 'mysql')) :param callable\_: A callable, which will be invoked with three positional arguments as well as optional keyword arguments: :ddl: This DDL element. :target: The :class:`_schema.Table` or :class:`_schema.MetaData` object which is the target of this event. May be None if the DDL is executed explicitly. :bind: The :class:`_engine.Connection` being used for DDL execution. May be None if this construct is being created inline within a table, in which case ``compiler`` will be present. :tables: Optional keyword argument - a list of Table objects which are to be created/ dropped within a MetaData.create_all() or drop_all() method call. :dialect: keyword argument, but always present - the :class:`.Dialect` involved in the operation. :compiler: keyword argument. Will be ``None`` for an engine level DDL invocation, but will refer to a :class:`.DDLCompiler` if this DDL element is being created inline within a table. :state: Optional keyword argument - will be the ``state`` argument passed to this function. :checkfirst: Keyword argument, will be True if the 'checkfirst' flag was set during the call to ``create()``, ``create_all()``, ``drop()``, ``drop_all()``. If the callable returns a True value, the DDL statement will be executed. :param state: any value which will be passed to the callable\_ as the ``state`` keyword argument. .. seealso:: :meth:`.SchemaItem.ddl_if` :class:`.DDLEvents` :ref:`event_toplevel`