Query.as_sql() generates invalid ORDER BY clause

[egenix_viktor]

Backend: SQLite

Test case: regressiontests/model_inheritance_regress

Statement: c1.get_next_by_pub_date()

The Query.as_sql() method in django.db.models.sql.query generates two ordering items for the same "model_inheritance_regress_article"."pub_date" field:

(The generated query has been split into multiple lines for readability.)

SELECT
    "model_inheritance_regress_article"."id",
    "model_inheritance_regress_article"."headline",
    "model_inheritance_regress_article"."pub_date",
    "model_inheritance_regress_articlewithauthor"."article_ptr_id",
    "model_inheritance_regress_articlewithauthor"."author"
FROM "model_inheritance_regress_articlewithauthor"
INNER JOIN "model_inheritance_regress_article"
ON ("model_inheritance_regress_articlewithauthor"."article_ptr_id" = "model_inheritance_regress_article"."id")
WHERE (
    "model_inheritance_regress_article"."pub_date" > %s OR  (
        "model_inheritance_regress_articlewithauthor"."article_ptr_id" > %s AND
        "model_inheritance_regress_article"."pub_date" = %s ))
ORDER BY
    "model_inheritance_regress_article"."pub_date" ASC,
    "model_inheritance_regress_article"."pub_date" DESC,
    "model_inheritance_regress_article"."headline" ASC
LIMIT 1

Parameters:

(u'2005-08-01 03:00:00', 1, u'2005-08-01 03:00:00')

It works on SQLite for some reason, but such an ORDER BY clause causes an error message on many database servers, such as on MS SQL Server 2005 (when used with another backend, certainly).

[Malcolm Tredinnick]

Nice catch. Looks like bad SQL indeed.

[Malcolm Tredinnick]

(In [9251]) Fixed #9406 -- Ensure that each database column is only represented once in the
"ORDER BY" clause of an SQL statement.

[Malcolm Tredinnick]

(In [9252]) [1.0.X] Fixed #9406 -- Ensure that each database column is only represented
once in the "ORDER BY" clause of an SQL statement.

Backport of r9251 from trunk.