aliased union in SQLAlchemy - sqlalchemy

Question

In sqlalchemy I am trying to union tables and then make alias with WHERE and ORDER_BY
something like
SELECT *
FROM (
SELECT [TABLE_ONE].[SOME_ID] AS [SOME_ID]
FROM [TABLE_ONE]
UNION
SELECT [TABLE_TWO].[SOME_ID] AS [SOME_ID]
FROM [TABLE_TWO]
) AS anon_1
WHERE ...
SQLAlchemy:
select_q = select([TABLE_ONE.c.SOME_ID], TABLE_ONE)
select_w = select([TABLE_TWO.c.SOME_ID], TABLE_TWO)
union_qw = union(select_q,select_w)
union_qw_aliased = aliased(union_qw)
s = select('*',union_qw_aliased)
but SQLAlchemy produces SQL code:
SELECT anon_1.[SOME_ID]
FROM (SELECT [TABLE_ONE].[SOME_ID] AS [SOME_ID]
FROM [TABLE_ONE] UNION SELECT [TABLE_TWO].[SOME_ID] AS [SOME_ID]
FROM [TABLE_TWO]) AS anon_1
WHERE SELECT [TABLE_ONE].[SOME_ID]
FROM [TABLE_ONE] UNION SELECT [TABLE_TWO].[SOME_ID]
FROM [TABLE_TWO]
Any help is appreciated

Answer 1

you're mis-using the second argument to "select()", which is actually the "whereclause" (though we encourage the use of the where() method these days). the FROM clause is usually implicit from the columns you're selecting. For your "select *", we can set an explicit FROM using select_from():
from sqlalchemy import *
m = MetaData()
t1 = Table('t1', m, Column('id', Integer))
t2 = Table('t2', m, Column('id', Integer))
select_q = select([t1])
select_w = select([t2])
union_qw = union(select_q, select_w)
union_qw_aliased = union_qw.alias()
s = select('*').select_from(union_qw_aliased)
print s
output:
SELECT *
FROM (SELECT t1.id AS id
FROM t1 UNION SELECT t2.id AS id
FROM t2) AS anon_1
to do more WHERE, add that using where() and do it against union_qw_aliased:
print s.where(union_qw_aliased.c.id == 5)
output:
SELECT *
FROM (SELECT t1.id AS id
FROM t1 UNION SELECT t2.id AS id
FROM t2) AS anon_1
WHERE anon_1.id = :id_1