On 02/02/2016 09:05 AM, Rick Otten wrote:
> However, when the fetch query actually runs, it includes the
non aliased
> table name as well as the aliased table name in the from
statement:
>
> select t.idfrom *some_table, some_table as t* where
t.some_column =
> /someValue/
well that's not a DELETE statement. query.delete() emits a DELETE
statement and you'd have to look in the SQL logs to see it.
There's no "bug" here as DELETE does not support deleting
directly from
an alias of a table; it's likely emitting DELETE .. FROM and
assuming
you want to do some kind of join against the aliased form of
your table.
Otherwise what SQL are you looking for this to produce that has
DELETE
but also an aliased form of the table?
I know that isn't the delete statement. It is the FETCH statement
before the delete is called.
http://docs.sqlalchemy.org/en/latest/orm/query.html#sqlalchemy.orm.query.Query.delete
oh im sorry, you mean the actual "SELECT" as part of the "fetch"
strategy. I wasn't sure what motivation there would be to send an
aliased table into delete(), as I think your DELETE statement is also
going to be not what you're expecting so that would be the more
immediate issue.
I have taken to the habit of using "aliased" for many of my sqlalchemy
queries because it makes it much easier for me to read the query on the
database when I have to troubleshoot an issue. Most queries are not as
simple as the example I posted.
OK, well sure, for a DELETE that doesn't really apply.
Aliased tables do not work with query.delete(), at least with
/synchronize_session='fetch'/. I can live with that. I was just
surprised by it and thought I'd share my experience.
Well an aliased table should probably not work with query.delete() ever,
because there's no SQL for that and otherwise the intention is not
clear. So this is a bug, thanks for reporting. At the very least it
should emit a warning.
As far as I can see, it *doesn't* work:
class A(Base):
__tablename__ = 'a'
id = Column(Integer, primary_key=True)
a1 = aliased(A)
s.query(a1).filter(a1.id == 5).delete(synchronize_session='fetch')
output:
sqlalchemy.exc.ProgrammingError: (ProgrammingError) missing FROM-clause
entry for table "a_1"
LINE 1: DELETE FROM a WHERE a_1.id = 5
^
'DELETE FROM a WHERE a_1.id = %(id_1)s' {'id_1': 5}
I apologize for not focusing on the "fetch" part of this but that
delete() even accepts the alias is a bigger issue, and I'm trying to
understand more fully what you're doing.
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