On Apr 16, 2009, at 2:31 PM, dykang wrote:

> inside = table.alias('inside')
>
> outside = inside.join(table, table.c.foo < 2)
> s = outside.select(use_labels=True).alias('outside')
>
> j = table2.join(s, table2.c.bar == outside.c.inside_foo)
>
> s = j.select(use_labels=True)
> rows = session.query(Test2).add_entity(Test, alias=inside).add_entity
> (Test, alias=outside).from_statement(s).all()

when you create a selectable, the columns on that selectable (i.e. the  
'.c.' namespace) are children of that selectable.   so if you had two  
selectables:

SELECT id, name FROM table

and

SELECT id, name FROM (select id, name FROM table)

both have "id" and "name" in their column list, but have a different  
parent selectable.     you could have instead said:

SELECT "something" AS id, name FROM (select id, name FROM table)

and its more apparent above how "id" means something different based  
on which selectable it belongs to.

So above, you're joining "table2" to "s".  the ON clause must be in  
terms of "table2" and "s", not "outside", which is meaningless in that  
context.


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