[sqlalchemy] Re: Table updates using data mapping
Thanks Mike, that clears up a few things On Jun 27, 2:08 am, Mike Orr [EMAIL PROTECTED] wrote: On 6/26/07, voltron [EMAIL PROTECTED] wrote: sess = create_session() allusers = sess.query(User).select() for user in allusers: user.group = contractor print x.name This adds the overhead of creating a Python object for every row. If you already have many of the objects in memory anyway or the overhead is too small to be noticeable, you can do it this way. Rick's way sends one small query to the database, which does it all internally. -- Mike Orr [EMAIL PROTECTED] --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: Table updates using data mapping
Updates and inserts on the ORM side of the street are single-object kinds of
things. The pattern is to load a list of objects, make the appropriate
modifications to the those in-memory objects, and then issue a session
flush().
This type of
bulk operation is best done with the SQL generation portion of the library,
like so (using an implicit bound connection here):
users.update(users.c.group == contractor).execute({users.c.group =
consultant})
On 6/26/07, voltron [EMAIL PROTECTED] wrote:
Could someone tell me how I would execute this SQL using data mapping?
# SQL
UPDATE users SET group=consultant WHERE group = contractor;
# Mapped object
user_mapper = mapper(User, users)
user = User()
Thanks
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[sqlalchemy] Re: Table updates using data mapping
would I have to do something like this? sess = create_session() allusers = sess.query(User).select() for user in allusers: user.group = contractor print x.name On Jun 26, 10:40 pm, voltron [EMAIL PROTECTED] wrote: Could someone tell me how I would execute this SQL using data mapping? # SQL UPDATE users SET group=consultant WHERE group = contractor; # Mapped object user_mapper = mapper(User, users) user = User() Thanks --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: Table updates using data mapping
On Jun 26, 2007, at 4:51 PM, Rick Morrison wrote:
Updates and inserts on the ORM side of the street are single-object
kinds of things. The pattern is to load a list of objects, make the
appropriate modifications to the those in-memory objects, and then
issue a session flush().
This type of bulk operation is best done with the SQL generation
portion of the library, like so (using an implicit bound connection
here):
users.update(users.c.group == contractor).execute({users.c.group
= consultant})
using the actual execution terminology i made up ! nice
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[sqlalchemy] Re: Table updates using data mapping
On 6/26/07, voltron [EMAIL PROTECTED] wrote: sess = create_session() allusers = sess.query(User).select() for user in allusers: user.group = contractor print x.name This adds the overhead of creating a Python object for every row. If you already have many of the objects in memory anyway or the overhead is too small to be noticeable, you can do it this way. Rick's way sends one small query to the database, which does it all internally. -- Mike Orr [EMAIL PROTECTED] --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
