Thanks Michael Bayer, i will try the Numeric type use “asdecimal=False”.
在 2014年1月22日星期三UTC+8上午1时50分06秒，Michael Bayer写道：
>
> yes I’ve just figured this out on this end - your column is not a Float,
> it is a Numeric (more specifically a DECIMAL, but Numeric is good enough).
>
> The column types that you place in Column have to match the *actual*
> datatype on the server - this is how SQLAlchemy knows what kind of data to
> expect. Otherwise, SQLAlchemy tries to save on performance by not
> unnecessarily converting data that should already be in the right format.
>
> To receive your numeric fields as floating point, you should be using the
> Numeric datatype, not Float, and use “asdecimal=False”.
>
> I’m still going to see if there’s an easy way to make this a little more
> resilient to mis-configuration, but that’s the fix for now. Here’s a demo:
>
> from sqlalchemy import *
>
> e = create_engine("mssql://scott:tiger@ms_2005", echo='debug')
>
> conn = e.connect()
> trans = conn.begin()
>
> t = Table('t', MetaData(), Column('data', Numeric(10, 5)))
> t.create(conn)
> conn.execute(t.insert().values(data="45.17"))
>
> t2 = Table('t', MetaData(), Column('data', Float()))
>
> print(conn.execute(t2.select()).fetchall())
>
> t3 = Table('t', MetaData(), Column('data', Numeric(asdecimal=False)))
>
> print(conn.execute(t3.select()).fetchall())
>
>
> On Jan 21, 2014, at 12:21 PM, 曹忠 <joo....@gmail.com <javascript:>> wrote:
>
> coefficient define on server:
>
> FCoefficient decimal(20, 10) NOT NULL DEFAULT (1),
>
> Float type has parameter asdecimal=False, 0.9 user no choice? I hope not
>
> 在 2014年1月21日星期二UTC+8下午10时59分07秒，Michael Bayer写道：
>>
>>
>> On Jan 21, 2014, at 4:31 AM, 曹忠 <joo....@gmail.com> wrote:
>>
>> > test env: sql server 2005 and pyodbc 3.0.7 and freetds 0.91, on debian
>> 8.0
>> > product env: sql server 2005 and pyodbc 3.0.7 and native client 10.0,
>> on windows 2003
>> > above two env is the same behavior with 0.9.1, always return decimal
>> object for float type
>> >
>> > follow is part data model:
>> >
>> > from sqlalchemy.ext.declarative import declarative_base
>> > from sqlalchemy.schema import Column,
>> > from sqlalchemy.types import SmallInteger, Integer, Float
>> > from sqlalchemy.types import String
>> >
>> > Base = declarative_base()
>> >
>> > class Unit(Base):
>> > __tablename__ = 't_MeasureUnit'
>> >
>> > id = Column('FMeasureUnitID', Integer, autoincrement=False,
>> primary_key=True)
>> > name = Column('FName', String(80), nullable=False)
>> > number = Column('FNumber', String(30), nullable=False)
>> > short_number = Column('FShortNumber', String(30))
>> > conversation = Column('FConversation', Integer,
>> server_default='(1)')
>> > coefficient = Column('FCoefficient', Float, nullable=False,
>> server_default='(1)')
>> > deleted = Column('FDeleted', SmallInteger, nullable=False,
>> server_default='(0)')
>> >
>> > with 0.8.4, conversation column return python float object, upgrade to
>> 0.9 or 0.9.1 all Float column always return decimal object.
>> > my project and the data model has been running for over two years, pass
>> two year with 0.7 and 0.8 no problem. my project not need to use decimal,
>> float precision is sufficient.
>>
>> uh, but “conversation” above is an Integer. What is the actual datatype
>> on SQL Server? Are you sure you’re not referring to “coefficient” ?
>>
>>
>>
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