[Sqlalchemy-tickets] Issue #3335: ordering by a label present in an `alias` will create an invalid query (zzzeek/sqlalchemy)

[jvanasco <iss...@bi...>]

New issue 3335: ordering by a label present in an `alias` will create an invalid query
https://bitbucket.org/zzzeek/sqlalchemy/issue/3335/ordering-by-a-label-present-in-an-alias

jvanasco:

this is a new issue with 1.0.0b2 and Postgres.  i am not sure if other databases will fail.  

this is a bit of an confusing to describe, so bear with me.  

i made an example, but it is confusing too!  

https://gist.github.com/jvanasco/986c30d91095cef5526f

the issue is in the interplay of aliased columns and an "ORDER BY"

If the ordering column's name is the same as a column name in the aliased "select", then an ordering will be applied to the column in the aliased select -- which breaks a GROUP BY.  if the column name is not in the aliased select, then the ordering will be generated as a bareword -- which is the valid query.

* query_form_a 
	this worked in 0.9.9, it does not work in 1.0.0b2
	
	line 100 applies a 'event_timestamp' label over the 'event_timestamp' column.
	line 110 sorts on 'event_timestamp'
	
	This will output 
		0.9.9	`ORDER BY event_timestamp DESC`
		1.0.0b2	`ORDER BY q_stream.event_timestamp DESC`

* query form b
	this did not work in 0.9.9 and does not work in 1.0.0b2
	just shown for comparison
	
	line 137 we select an 'event_timestamp' column
	line 147 sorts on 'event_timestamp'


* query form c
	this works on 0.9.9 and 1.0.0b2 however it requires a column renaming

	line 174 we select the 'event_timestamp' column and rename it 'timestamp_renamed'
	line 184 sorts on 'timestamp_renamed'

	This will output 
		0.9.9 	`ORDER BY timestamp_renamed DESC`
		1.0.0b2 `ORDER BY timestamp_renamed DESC`

note: i used the following sqlalchemy connection string so it would hit the DB and raise the query exceptions for postgres.  i found that easier than inspecting the sql in a memory engine.
    user - sqlalchemy_test
    password - sqla
    database - sqlalchemy_test