This is a duplicate mail (due to a recent SMTP problems). Don't reply.
DS
ml píše v Po 11. 12. 2006 v 23:13 +0100:
> Hi!
>
> I have a little questions about how does the SA work:
>
> Example:
> ========
> I borrowed a model from SA documentation example User/Address. My mapper
> is
>
> mapper(Address, addresses_table)
> mapper(User, users_table, properties = {
> 'addresses' : relation(Address, cascade="all, delete-orphan")
> }
> )
>
> My example code:
> ----------------
> u = User("a", "b")
> u.addresses.append(Address("1","2","3","4"))
> u.addresses.append(Address("1","2","3","4"))
> session.save(u)
> session.flush()
> session.clear()
> print "**********"
> u = session.query(User).get_by_user_name("a")
> session.delete(u)
> session.flush()
>
> Output:
> -----------
> BEGIN
> INSERT INTO users (user_name, password) VALUES (?, ?)
> ['a', 'b']
> INSERT INTO addresses (user_id, street, city, state, zip) VALUES
> (?, ?, ?, ?, ?)
> [1, '1', '2', '3', '4']
> INSERT INTO addresses (user_id, street, city, state, zip) VALUES
> (?, ?, ?, ?, ?)
> [1, '1', '2', '3', '4']
> COMMIT
> **********
> SELECT users.user_name AS users_user_name, users.password AS
> users_password, users.user_id AS users_user_id
> FROM users
> WHERE users.user_name = ? ORDER BY users.oid
> LIMIT 1 OFFSET 0
> ['a']
> BEGIN
> SELECT addresses.city AS addresses_city, addresses.address_id AS
> addresses_address_id, addresses.user_id AS addresses_user_id,
> addresses.zip AS addresses_zip, addresses.state AS addresses_state,
> addresses.street AS addresses_street
> FROM addresses
> WHERE ? = addresses.user_id ORDER BY addresses.oid
> [1]
> DELETE FROM addresses WHERE addresses.address_id = ?
> [[1], [2]]
> DELETE FROM users WHERE users.user_id = ?
> [1]
> COMMIT
>
> Question about deleting:
> ------------------------
> 1) Why does the SA the second SELECT for addresses to obtain primary
> keys? Why there is not a direct "DELETE FROM addresses WHERE user_id=?"?
> 2) If it is neccessary to do this SELECT, why is the SA selecting all
> columns? E.g. I will have 1 user with 100000 addresses - an idea of
> selecting all 100000 addresses to get their id's is spooky :-)
>
> Why is it so or em I missing something?
>
> Thank you.
>
> David
>
>
>
> >
--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---
