Re: [Django] #28787: QuerySet.update() fails on MySQL if a subquery references the base table

[Django]

#28787: QuerySet.update() fails on MySQL if a subquery references the base table
-+-
 Reporter:  Paulo|Owner:  nobody
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  1.11
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  invalid
 Keywords:   | Triage Stage:  Accepted
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Oskar Persson):

 Replying to [comment:4 Sonu kumar]:
 > This doesn't look to be a bug in Django. This is a more of MySQL query
 parser bug.

 This is not a query parser bug but a documented limitation of
 [https://dev.mysql.com/doc/refman/5.7/en/subquery-errors.html MySQL]:

 > You can use a subquery for assignment within an UPDATE statement because
 subqueries are legal in UPDATE and DELETE statements as well as in SELECT
 statements. However, you cannot use the same table (in this case, table
 t1) for both the subquery FROM clause and the update target.

 and [https://mariadb.com/kb/en/library/subquery-limitations/#modifying-
 and-selecting-from-the-same-table MariaDB]:

 > It's not possible to both modify and select from the same table in a
 subquery. For example:
 > {{{
 > DELETE FROM staff WHERE name = (SELECT name FROM staff WHERE age=61);
 > ERROR 1093 (HY000): Table 'staff' is specified twice, both
 >   as a target for 'DELETE' and as a separate source for data
 > }}}

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Re: [Django] #28787: QuerySet.update() fails on MySQL if a subquery references the base table

[Django]

#28787: QuerySet.update() fails on MySQL if a subquery references the base table
-+-
 Reporter:  Paulo|Owner:  nobody
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  1.11
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  invalid
 Keywords:   | Triage Stage:  Accepted
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Sonu kumar):

 * status:  new => closed
 * resolution:   => invalid


Comment:

 This doesn't look to be a bug in Django. This is a more of MySQL query
 parser bug.

 Query generated by Django ORM


 {{{
 UPDATE `CoreApp_room` SET `name` = 'suite'
 WHERE `CoreApp_room`.`house_id` IN
 ( SELECT U0.`id` FROM `CoreApp_house` U0
INNER JOIN `CoreApp_room` U1
   ON (U0.`id` = U1.`house_id`)
   WHERE U1.`name` LIKE '%suite%'
 )
 }}}

 As we can the query generated by Django is totally valid but MySQL server
 has raise error

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Re: [Django] #28787: QuerySet.update() fails on MySQL if a subquery references the base table

[Django]

#28787: QuerySet.update() fails on MySQL if a subquery references the base table
-+-
 Reporter:  Paulo|Owner:  nobody
 Type:  Bug  |   Status:  new
Component:  Database layer   |  Version:  1.11
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:   | Triage Stage:  Accepted
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by felixxm):

 * cc: felixxm (added)


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Re: [Django] #28787: QuerySet.update() fails on MySQL if a subquery references the base table (was: MySQL Update fails)

[Django]

#28787: QuerySet.update() fails on MySQL if a subquery references the base table
-+-
 Reporter:  Paulo|Owner:  nobody
 Type:  Bug  |   Status:  new
Component:  Database layer   |  Version:  1.11
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:   | Triage Stage:  Accepted
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Tim Graham):

 * component:  Uncategorized => Database layer (models, ORM)
 * stage:  Unreviewed => Accepted
 * type:  Uncategorized => Bug


Old description:

> Given the models below:
>

> {{{
> class House(models.Model):
> name = models.CharField(max_length=200)
>
> class Room(models.Model):
> name = models.CharField(max_length=200)
> house = models.ForeignKey(House, on_delete=models.CASCADE)
> }}}
>

> The following query fails:
>

> {{{
> houses_with_suites = House.objects.filter(room__name__icontains='suite')
> Room.objects.filter(house__in=houses_with_suites).update(name='suite')
> }}}
>
> With this error:
>

> {{{
> OperationalError: (1093, "You can't specify target table
> 'mysql_test_room' for update in FROM clause")
> }}}
>
> I think this has been around for a while
> (https://code.djangoproject.com/ticket/20300).
>
> I've confirmed this only happens in MySQL. It works on PostgresSQL and
> SQLite.

New description:

 Given the models below:


 {{{
 class House(models.Model):
 name = models.CharField(max_length=200)

 class Room(models.Model):
 name = models.CharField(max_length=200)
 house = models.ForeignKey(House, on_delete=models.CASCADE)
 }}}


 The following query fails:


 {{{
 houses_with_suites = House.objects.filter(room__name__icontains='suite')
 Room.objects.filter(house__in=houses_with_suites).update(name='suite')
 }}}

 With this error:


 {{{
 OperationalError: (1093, "You can't specify target table 'mysql_test_room'
 for update in FROM clause")
 }}}

 I think this has been around for a while (#20300).

 I've confirmed this only happens in MySQL. It works on PostgresSQL and
 SQLite.

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