[Sqlalchemy-tickets] Issue #3424: mssql aliasing of schema-tables in update (zzzeek/sqlalchemy)

[Andrey Z. <iss...@bi...>]

New issue 3424: mssql aliasing of schema-tables in update
https://bitbucket.org/zzzeek/sqlalchemy/issue/3424/mssql-aliasing-of-schema-tables-in-update

Andrey Zholos:

When updating a table with a specified schema name, some parts of the generated statement refer to the table with an alias and some parts don't.

A subquery uses an alias that was not introduced (it could be introduced in an mssql "from" clause):
```
#!sql
UPDATE [schema].sometable SET val=
(SELECT [#other].newval FROM [#other] WHERE sometable_1.sym = [#other].sym)
```

An alias is introduced but the "where" clause doesn't use it:
```
#!sql
UPDATE [schema].sometable SET val=[#other].newval
FROM [schema].sometable AS sometable_1, [#other]
WHERE [schema].sometable.sym = [#other].sym
```

Both of these statements fail. Complete program attached.