Class DropConstraint

lib/sqlalchemy/sql/ddl.py:789–827

Represent an ALTER TABLE DROP CONSTRAINT statement.

class DropConstraint(_DropBase["Constraint"]):
    """Represent an ALTER TABLE DROP CONSTRAINT statement."""

    __visit_name__ = "drop_constraint"

    def __init__(
        self,
        element: Constraint,
        *,
        cascade: bool = False,
        if_exists: bool = False,
        isolate_from_table: bool = True,
        **kw: Any,
    ) -> None:
        """Construct a new :class:`.DropConstraint` construct.

        :param element: a :class:`.Constraint` object
        :param cascade: optional boolean, indicates backend-specific
         "CASCADE CONSTRAINT" directive should be rendered if available
        :param if_exists: optional boolean, indicates backend-specific
         "IF EXISTS" directive should be rendered if available
        :param isolate_from_table: optional boolean, defaults to True.  Has
         the effect of the incoming constraint being isolated from being
         included in a CREATE TABLE sequence when associated with a
         :class:`.Table`.

         .. versionadded:: 2.0.39 - added
            :paramref:`.DropConstraint.isolate_from_table`, defaulting
            to True.  Previously, the behavior of this parameter was implicitly
            turned on in all cases.

        """
        self.cascade = cascade
        super().__init__(element, if_exists=if_exists, **kw)

        if isolate_from_table:
            element._create_rule = util.portable_instancemethod(
                self._create_rule_disable
            )


class SetTableComment(_CreateDropBase["Table"]):