Module « sqlalchemy »

Fonction column - module sqlalchemy

Signature de la fonction column

def column(text, type_=None, is_literal=False, _selectable=None) 

Description

column.__doc__

Produce a :class:`.ColumnClause` object.

        The :class:`.ColumnClause` is a lightweight analogue to the
        :class:`_schema.Column` class.  The :func:`_expression.column`
        function can
        be invoked with just a name alone, as in::

            from sqlalchemy import column

            id, name = column("id"), column("name")
            stmt = select(id, name).select_from("user")

        The above statement would produce SQL like::

            SELECT id, name FROM user

        Once constructed, :func:`_expression.column`
        may be used like any other SQL
        expression element such as within :func:`_expression.select`
        constructs::

            from sqlalchemy.sql import column

            id, name = column("id"), column("name")
            stmt = select(id, name).select_from("user")

        The text handled by :func:`_expression.column`
        is assumed to be handled
        like the name of a database column; if the string contains mixed case,
        special characters, or matches a known reserved word on the target
        backend, the column expression will render using the quoting
        behavior determined by the backend.  To produce a textual SQL
        expression that is rendered exactly without any quoting,
        use :func:`_expression.literal_column` instead,
        or pass ``True`` as the
        value of :paramref:`_expression.column.is_literal`.   Additionally,
        full SQL
        statements are best handled using the :func:`_expression.text`
        construct.

        :func:`_expression.column` can be used in a table-like
        fashion by combining it with the :func:`.table` function
        (which is the lightweight analogue to :class:`_schema.Table`
        ) to produce
        a working table construct with minimal boilerplate::

            from sqlalchemy import table, column, select

            user = table("user",
                    column("id"),
                    column("name"),
                    column("description"),
            )

            stmt = select(user.c.description).where(user.c.name == 'wendy')

        A :func:`_expression.column` / :func:`.table`
        construct like that illustrated
        above can be created in an
        ad-hoc fashion and is not associated with any
        :class:`_schema.MetaData`, DDL, or events, unlike its
        :class:`_schema.Table` counterpart.

        .. versionchanged:: 1.0.0 :func:`_expression.column` can now
           be imported from the plain ``sqlalchemy`` namespace like any
           other SQL element.

        :param text: the text of the element.

        :param type: :class:`_types.TypeEngine` object which can associate
          this :class:`.ColumnClause` with a type.

        :param is_literal: if True, the :class:`.ColumnClause` is assumed to
          be an exact expression that will be delivered to the output with no
          quoting rules applied regardless of case sensitive settings. the
          :func:`_expression.literal_column()` function essentially invokes
          :func:`_expression.column` while passing ``is_literal=True``.

        .. seealso::

            :class:`_schema.Column`

            :func:`_expression.literal_column`

            :func:`.table`

            :func:`_expression.text`

            :ref:`sqlexpression_literal_column`