On 12 Set, 19:31, "Rick Morrison" <[EMAIL PROTECTED]> wrote:
> SQL Server provides no facilities for retrieving a GUID key after an insert
> -- it's not a true autoincrementing key. The MSSQL driver for SA uses either
> @@IDENTITY or SCOPE_IDENTITY() to retreive the most-recently inserted
> autoincrement value, but there is no such facility for getting GUID keys.
>
> SA provides a mechanism called "passive default" to handle these kinds of
> things. What it does under the covers, or what you can do explicitly without
> it is:
>
> a) first call newid() to get the new GUID
> b) then do the insert using the GUID value as a normal attribute
>
> My personal opinion is that GUID keys are over-utilized, and there are
> usually better alternatives that will perform better overall, and will not
> make you swim upstream with SA.
Ok... In the meanwhile i've tryied to play a little bit and found that
if i just change the pk from the guid to another(s) column(s)
everything works great. Probably this is the right occasion for me to
sanitize clean up e refactor this application database design... :)
Here's a link to an article about an
> alternate scheme to get rid of GUID keys that talks about performance
> implications, I'm sure you can find more if you look:
>
> http://www.sql-server-performance.com/articles/per/guid_performance_p...
Thans much! :)
FP
>
> Rick
>
> On 9/12/07, Smoke <[EMAIL PROTECTED]> wrote:
>
>
>
> > Still have problems...
>
> > if i change:
>
> > t = sa.Table("Machines", metadata, autoload=True)
>
> > to:
>
> > t = sa.Table("Rpm_MacchineConfig", metadata,
> > sa.Column('uId', sa.databases.mssql.MSUniqueIdentifier,
> > primary_key=True),
> > autoload=False)
>
> > i have:
>
> > sqlalchemy.exceptions.DBAPIError: (ProgrammingError) ('42000',
> > "[42000] [Microso
> > ft][ODBC SQL Server Driver][SQL Server]Incorrect syntax near
> > ')'. (102)") u'INSERT INTO [Rpm_MacchineConfig] () VALUES ()' []
>
> > and if i put autoload= True, like this:
>
> > t = sa.Table("Rpm_MacchineConfig", metadata,
> > sa.Column('uId', sa.databases.mssql.MSUniqueIdentifier,
> > primary_key=True),
> > autoload=True)
>
> > i have this:
>
> > sqlalchemy.exceptions.DBAPIError: (IntegrityError) ('23000', "[23000]
> > [Microsoft
> > ][ODBC SQL Server Driver][SQL Server]Impossible to insert NULL value
> > into column 'uId' on table 'dbtests.dbo.Rpm_MachineConfig'.The column
> > does not support NULL values.... (515); [01000] [Microsoft][O
> > DBC SQL Server Driver][SQL Server]Instruction interrupted. (3621)") u
> > 'INSERT INTO [Rpm_MacchineConfig] (nome, nodo, descrizione) VALUES
> > (?, ?, ?)' ['MARIO', 'FI', None ]
>
> > Any hint before i start changing my table design? I'm a newbie on
> > sqlalchemy so i'm probably missing something...
>
> > thanks
>
> > FP
>
> > On 12 Set, 02:18, KyleJ <[EMAIL PROTECTED]> wrote:
> > > You probably need to override the autoloaded primary key column:
> >http://www.sqlalchemy.org/docs/04/metadata.html#metadata_tables_refle...
>
> > > Specify the type with MSUniqueIdentifier from
> > > sqlalchemy.databases.mssql
>
> > > On Sep 11, 9:01 am, Smoke <[EMAIL PROTECTED]> wrote:
>
> > > > Hi All,
>
> > > > I'm new to sqlalchemy and was checking if i can introduce it into some
> > > > of my projects... I have some database ( sql server ) tables with
> > > > MSUniqueidenfier columns set as PK and with newid() as default
> > > > values...
> > > > So, if i try to map this table into a class,save a new record and
> > > > flush, then i have errors because it says that column doesn't support
> > > > NULL values..
> > > > Is there any option i'm missing that can make me exclude this PK from
> > > > the INSERT query or somehow tell sqlalchemy that this pk column value
> > > > is autogenerated by the database?
>
> > > > thanks,
> > > > FP
>
> > > > P.S.:
>
> > > > My code is something very simple... like this:
>
> > > > t = sa.Table("Machines", metadata, autoload=True)
> > > > Session = sessionmaker(bind=db, autoflush=False, transactional=False)
> > > > class Machine(object):
> > > > pass
>
> > > > session = Session()
> > > > sa.orm.mapper(Machine, t)#, exclude_properties=['uId'])
> > > > m = Machine()
>
> > > > nm = Machine()
> > > > nm.name, nm.node = "Mac1", "P"
> > > > session.save(nm)
> > > > session.flush()
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