#30009: Invalid SQL query when using Subquery, caused by table alias quoting.
-------------------------------------+-------------------------------------
               Reporter:  datamik    |          Owner:  nobody
                   Type:  Bug        |         Status:  new
              Component:  Database   |        Version:  1.11
  layer (models, ORM)                |
               Severity:  Normal     |       Keywords:  queryset subquery
           Triage Stage:             |      Has patch:  0
  Unreviewed                         |
    Needs documentation:  0          |    Needs tests:  0
Patch needs improvement:  0          |  Easy pickings:  0
                  UI/UX:  0          |
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 It seems that table aliases quoting issue reported in
 [https://code.djangoproject.com/ticket/27862 #27862] ticket still exists.

 This happens when Django is configured with PostgreSQL backend.

 to reproducing it use following models:

 {{{
 class Case(models.Model):
     case_number = models.CharField(max_length=32)
     parent_case = models.ForeignKey('self', null=True, blank=True)


 class Subject(models.Model):
     name = models.CharField(max_length=128)
     case = models.ForeignKey(Case)


 class Task(models.Model):
     num = models.CharField(max_length=32, blank=True)
     case = models.ForeignKey(Case, null=True, blank=True)
 }}}

 and then:

 {{{
 Task.objects.annotate(
     top_case_id=Coalesce(F('case__parent_case__parent_case_id'),
 F('case__parent_case_id'), F('case_id')),
 subject=Subquery(Subject.objects.filter(case_id=OuterRef('top_case_id')))
 ).all()
 }}}

 Following SQL is generated:

 {{{
 SELECT
   "test_app_task"."id",
   "test_app_task"."num",
   "test_app_task"."case_id",
   COALESCE(T3."parent_case_id", "test_app_case"."parent_case_id",
 "test_app_task"."case_id") AS "top_case_id",
   (SELECT
     U0."id",
     U0."name",
     U0."case_id"
   FROM "test_app_subject" U0
   WHERE U0."case_id" = (COALESCE("T3"."parent_case_id",
 "test_app_case"."parent_case_id", "test_app_task"."case_id"))) AS
 "subject"
 FROM "test_app_task" LEFT OUTER JOIN
   "test_app_case" ON ("test_app_task"."case_id" = "test_app_case"."id")
 LEFT OUTER JOIN
   "test_app_case" T3 ON ("test_app_case"."parent_case_id" = T3."id")
 }}}

 Error:

 {{{
 ProgrammingError: missing FROM-clause entry for table "T3"
 LINE 1: ...st_app_subject" U0 WHERE U0."case_id" = (COALESCE("T3"."pare...
 }}}

 SQL works as expected, when quotes are removed from T3 alias.

-- 
Ticket URL: <https://code.djangoproject.com/ticket/30009>
Django <https://code.djangoproject.com/>
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