yah a little bug there, exists() was degined to be used in WHERE
criterion but not as a standalone. theres a tweak in r2358 where it
will suppress its "FROM" list in a select the way you were trying to
do.
On Feb 23, 10:25 am, Manlio Perillo <[EMAIL PROTECTED]> wrote:
> Hi.
>
> I'm having problems with the exists clause.
>
> Here is the code:
>
> from sqlalchemy import *
>
> db = create_engine('sqlite:///', echo=True)
> metadata = BoundMetaData(db)
>
> test = Table(
> 'test', metadata,
> Column('id', Integer, primary_key=True),
> Column('x', String),
> Column('y', String)
> )
>
> metadata.create_all()
> try:
> conn = db.contextual_connect()
>
> # i = test.insert()
> # conn.execute(i, x='x', y='z')
>
> # Test if select works without a from clause
> query = select([text('1 + 1')])
> print conn.execute(query).scalar()
>
> query = select(
> [exists(
> [test.c.id],
> and_(
> test.c.x == 'x',
> test.c.y == 'y'
> )
> )]
> )
> print conn.execute(query).scalar()
> finally:
> metadata.drop_all()
>
> The generated query is:
>
> SELECT EXISTS (SELECT test.id AS id
> FROM test
> WHERE test.x = ? AND test.y = ?)
> FROM (SELECT test.id AS id
> FROM test
> WHERE test.x = ? AND test.y = ?)
>
> This is wrong (it works on SQLite but Postgres raises an error).
> I have tried to add a from_obj=[], but it does not works.
>
> Thanks and regards Manlio Perillo
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