sqlalchemy.sql.sqltypes.Numeric

Construct a Numeric. :param precision: the numeric precision for use in DDL ``CREATE TABLE``. :param scale: the numeric scale for use in DDL ``CREATE TABLE``. :param asdecimal: default True. Return whether or not values should be sent as Python Decimal objects, or as floats. Different DBAPIs send one or the other based on datatypes - the Numeric type will ensure that return values are one or the other across DBAPIs consistently. :param decimal_return_scale: Default scale to use when converting from floats to Python decimals. Floating point values will typically be much longer due to decimal inaccuracy, and most floating point database types don't have a notion of "scale", so by default the float type looks for the first ten decimal places when converting. Specifying this value will override that length. Types which do include an explicit ".scale" value, such as the base :class:`.Numeric` as well as the MySQL float types, will use the value of ".scale" as the default for decimal_return_scale, if not otherwise specified. When using the ``Numeric`` type, care should be taken to ensure that the asdecimal setting is appropriate for the DBAPI in use - when Numeric applies a conversion from Decimal->float or float-> Decimal, this conversion incurs an additional performance overhead for all result columns received. DBAPIs that return Decimal natively (e.g. psycopg2) will have better accuracy and higher performance with a setting of ``True``, as the native translation to Decimal reduces the amount of floating- point issues at play, and the Numeric type itself doesn't need to apply any further conversions. However, another DBAPI which returns floats natively *will* incur an additional conversion overhead, and is still subject to floating point data loss - in which case ``asdecimal=False`` will at least remove the extra conversion overhead.

Return a conversion function for processing bind values. Returns a callable which will receive a bind parameter value as the sole positional argument and will return a value to send to the DB-API. If processing is not necessary, the method should return ``None``. .. note:: This method is only called relative to a **dialect specific type object**, which is often **private to a dialect in use** and is not the same type object as the public facing one, which means it's not feasible to subclass a :class:`.types.TypeEngine` class in order to provide an alternate :meth:`_types.TypeEngine.bind_processor` method, unless subclassing the :class:`_types.UserDefinedType` class explicitly. To provide alternate behavior for :meth:`_types.TypeEngine.bind_processor`, implement a :class:`_types.TypeDecorator` class and provide an implementation of :meth:`_types.TypeDecorator.process_bind_param`. .. seealso:: :ref:`types_typedecorator` :param dialect: Dialect instance in use.

Return the corresponding type object from the underlying DB-API, if any. This can be useful for calling ``setinputsizes()``, for example.

Return a conversion function for processing literal values that are to be rendered directly without using binds. This function is used when the compiler makes use of the "literal_binds" flag, typically used in DDL generation as well as in certain scenarios where backends don't accept bound parameters. Returns a callable which will receive a literal Python value as the sole positional argument and will return a string representation to be rendered in a SQL statement. .. note:: This method is only called relative to a **dialect specific type object**, which is often **private to a dialect in use** and is not the same type object as the public facing one, which means it's not feasible to subclass a :class:`.types.TypeEngine` class in order to provide an alternate :meth:`_types.TypeEngine.literal_processor` method, unless subclassing the :class:`_types.UserDefinedType` class explicitly. To provide alternate behavior for :meth:`_types.TypeEngine.literal_processor`, implement a :class:`_types.TypeDecorator` class and provide an implementation of :meth:`_types.TypeDecorator.process_literal_param`. .. seealso:: :ref:`types_typedecorator`

Return a conversion function for processing result row values. Returns a callable which will receive a result row column value as the sole positional argument and will return a value to return to the user. If processing is not necessary, the method should return ``None``. .. note:: This method is only called relative to a **dialect specific type object**, which is often **private to a dialect in use** and is not the same type object as the public facing one, which means it's not feasible to subclass a :class:`.types.TypeEngine` class in order to provide an alternate :meth:`_types.TypeEngine.result_processor` method, unless subclassing the :class:`_types.UserDefinedType` class explicitly. To provide alternate behavior for :meth:`_types.TypeEngine.result_processor`, implement a :class:`_types.TypeDecorator` class and provide an implementation of :meth:`_types.TypeDecorator.process_result_value`. .. seealso:: :ref:`types_typedecorator` :param dialect: Dialect instance in use. :param coltype: DBAPI coltype argument received in cursor.description.