Referencing a superselect's column by it's declared alias from a subselect fails

In the following statement (which works), if I s/ps."usesysid"/"UID"/ in the
two innermost subselects (such that it refers to the declared alias rather
than the true column name), it fails. In DB2, it works in similar
situations.

create view "users" as
select ps."usesysid" as "UID",
ps."usename" as "Username",
ps."passwd" as "Password",
coalesce (
(
select cast (ui."info_value" as integer)
from only "user_info" as "ui"
inner join only "user_info_types" as "uit"
on uit."type_id" = ui."info_type_id"
where uit."info_type" = 'Position ID'
and uit."info_type_name" = 'Default'
and ui."user_id" = ps."usesysid"
),
0
) as "Position ID",
coalesce (
(
select cast (ui."info_value" as integer)
from only "user_info" as "ui"
inner join only "user_info_types" as "uit"
on uit."type_id" = ui."info_type_id"
where uit.info_type = 'Creator ID'
and uit.info_type_name = 'Default'
and ui."user_id" = ps."usesysid"
),
0
) as "Creator ID"
from only "pg_shadow" as "ps"
order by "UID";

--
Casey Allen Shobe / Network Security Analyst & PHP Developer
SecureWorks, Inc. / 404.327.6339 x169 / Fax: 404.728.0144
cshobe(at)secureworks(dot)net / http://www.secureworks.net
Content is my own and does not necessarily represent my company.

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