Method scalar_subquery

lib/sqlalchemy/sql/selectable.py:3732–3759

Return a 'scalar' representation of this selectable, which can be used as a column expression. The returned object is an instance of :class:`_sql.ScalarSelect`. Typically, a select statement which has only one column in its columns clause is eligible to be used as a

(self)

        return Exists(self)

    def scalar_subquery(self) -> ScalarSelect[Any]:
        """Return a 'scalar' representation of this selectable, which can be
        used as a column expression.

        The returned object is an instance of :class:`_sql.ScalarSelect`.

        Typically, a select statement which has only one column in its columns
        clause is eligible to be used as a scalar expression.  The scalar
        subquery can then be used in the WHERE clause or columns clause of
        an enclosing SELECT.

        Note that the scalar subquery differentiates from the FROM-level
        subquery that can be produced using the
        :meth:`_expression.SelectBase.subquery`
        method.

        .. versionchanged: 1.4 - the ``.as_scalar()`` method was renamed to
           :meth:`_expression.SelectBase.scalar_subquery`.

        .. seealso::

            :ref:`tutorial_scalar_subquery` - in the 2.0 tutorial

        """
        if self._label_style is not LABEL_STYLE_NONE:
            self = self.set_label_style(LABEL_STYLE_NONE)

        return ScalarSelect(self)

    def label(self, name: Optional[str]) -> Label[Any]:
        """Return a 'scalar' representation of this selectable, embedded as a