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SQLAlchemy joins table from subquery. How to prevent it of doing this?

I have this subquery:
aliasBilling = aliased(Billing)
subQueryReversesBilling = db.session.query(BillingReversal).select_from(BillingReversal).with_entities(BillingReversal.reverses_billing_id).filter(BillingReversal.billing_id == aliasBilling.id).subquery()
Which generates:
SELECT billing_reversal.reverses_billing_id
FROM billing_reversal, billing AS billing_1
WHERE billing_reversal.billing_id = billing_1.id
How to get rid of that join(comma style) I didn't specified as it makes a join for the full table and every record. Apparently it is assuming I need it as it is in the filtering part(where clause), but I take that table from the bigger query I have later on. That is why it is a subquery. What I need is this:
SELECT billing_reversal.reverses_billing_id
FROM billing_reversal
WHERE billing_reversal.billing_id = billing_1.id

The cross join is coming from the aliased Billing table in the filter clause.
If BillingReversal and Billing are linked with a relationship (and a foreign key), you should leverage this relationship and join instead of filter.
subQueryReversesBilling = (
db.session.query(BillingReversal)
.join(Billing, BillingReversal.billing)
.with_entities(BillingReversal.id)
.subquery()
)

SELECT DISTINCT FROM <subquery> GROUP BY HAVING Query in SQLAlchemy

I want to write a query in SQLAlchemy, which is the equivalent of the following,
SELECT DISTINCT <column>
FROM <subquery> AS result
GROUP BY <columns>
HAVING COUNT(*) = 1
I already have the subquery that I want to use, but I am not sure how to add the rest of it. How can I implement this?

Update Django model based on the row number of rows produced by a subquery on the same model

I have a PostgreSQL UPDATE query which updates a field (global_ranking) of every row in a table, based on the ROW_NUMBER() of each row in that same table sorted by another field (rating). Additionally, the update is partitioned, so that the ranking of each row is relative only to those rows which belong to the same language.
In short, I'm updating the ranking of each player in a game, based on their current rating.
The PostgreSQL query looks like this:
UPDATE stats_userstats
SET
global_ranking = sub.row_number
FROM (
SELECT id, ROW_NUMBER() OVER (
PARTITION BY language
ORDER BY rating DESC
) AS row_number
FROM stats_userstats
) sub
WHERE stats_userstats.id = sub.id;
I'm also using Django, and it'd be fun to learn how to express this query using the Django ORM, if possible.
At first, it seemed like Django had everything necessary to express the query, including the ability to use PostgreSQL's ROW_NUMBER() windowing function, but my best attempt updates all rows ranking with 1:
from django.db.models import F, OuterRef, Subquery
from django.db.models.expressions import Window
from django.db.models.functions import RowNumber
UserStats.objects.update(
global_ranking=Subquery(
UserStats.objects.filter(
id=OuterRef('id')
).annotate(
row_number=Window(
expression=RowNumber(),
partition_by=[F('language')],
order_by=F('rating').desc()
)
).values('row_number')
)
)
I used from django.db import connection; print(connection.queries) to see the query produced by that Django ORM statement, and got this vaguely similar SQL statement:
UPDATE "stats_userstats"
SET "global_ranking" = (
SELECT ROW_NUMBER() OVER (
PARTITION BY U0."language"
ORDER BY U0."rating" DESC
) AS "row_number"
FROM "stats_userstats" U0
WHERE U0."id" = "stats_userstats"."id"
It looks like what I need to do is move the subquery from the SET portion of the query to the FROM, but it's unclear to me how to restructure the Django ORM statement to achieve that.
Any help is greatly appreciated. Thank you!

Subquery filters qs by provided OuterRef. You're always getting 1 as each user is in fact first in any ranking if only them are considered.
A "correct" query would be:
UserStats.objects.alias(
row_number=Window(
expression=RowNumber(),
partition_by=[F('language')],
order_by=F('rating').desc()
)
).update(global_ranking=F('row_number'))
But Django will not allow that:
django.core.exceptions.FieldError: Window expressions are not allowed in this query
Related Django ticket: https://code.djangoproject.com/ticket/25643
I think you might comment there with your use case.

SQLite Inner Join with Limit on Left Table

Firstly, let me describe a scenario similar to the one I am facing; to better explain my issue. In this scenario, I am creating a system which needs to select 'n' random blog posts from a table and then get all the replies for those selected posts.
Imagine my structure like so:
blog_posts(id INTEGER PRIMARY KEY, thepost TEXT)
blog_replies(id INTEGER PRIMARY KEY, postid INTEGER FOREIGN KEY REFERENCES blog_posts(id), thereply TEXT)
This is the current SQL I have, but am getting an error:
SELECT blog_post.id, blog_post.thepost, blog_replies.id, blog_replies.thereply
FROM (SELECT blog_post.id, blog_post.thepost FROM blog_post ORDER BY RANDOM() LIMIT ?)
INNER JOIN blog_replies
ON blog_post.id=blog_replies_options.postid;
Here is the error:
sqlite3.OperationalError: no such column: hmquestion.id

Your query needs an alias added to the subquery. This will allow you to reference the fields from your subquery within the outer query:
SELECT hmquestion.id, hmquestion.question,
hmquestion_options.id, hmquestion_options.option
FROM (SELECT hmquestion.id, hmquestion.question
FROM hmquestion ORDER BY RANDOM() LIMIT ?) AS hmquestion <--Add Alias Here
INNER JOIN hmquestion_options
ON hmquestion.id=hmquestion_options.questionid;
As is, you're outer query doesn't know what hmquestion references.

Include non-column value in sqlalchemy query

How do I do this in sqlalchemy SELECT column1, 'Table1' as TableName
FROM Table1?
Specifically the 'Table1' as TableName part.
I want this so that I can know which table a row came from in a union query I am doing. Apologies if this should be simple but I spent at least an hour trying to figure it out.

Use literal_column:
select([t1.c.col1, literal_column("t1", type_=Unicode).label("TableName")])