#28787 closed Bug (invalid)
QuerySet.update() fails on MySQL if a subquery references the base table
Reported by: | Paulo | Owned by: | nobody |
---|---|---|---|
Component: | Database layer (models, ORM) | Version: | 1.11 |
Severity: | Normal | Keywords: | |
Cc: | Mariusz Felisiak | Triage Stage: | Accepted |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description (last modified by )
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.
Change History (5)
comment:1 by , 7 years ago
Description: | modified (diff) |
---|
comment:2 by , 7 years ago
Component: | Uncategorized → Database layer (models, ORM) |
---|---|
Description: | modified (diff) |
Summary: | MySQL Update fails → QuerySet.update() fails on MySQL if a subquery references the base table |
Triage Stage: | Unreviewed → Accepted |
Type: | Uncategorized → Bug |
comment:3 by , 7 years ago
Cc: | added |
---|
follow-up: 5 comment:4 by , 7 years ago
Resolution: | → invalid |
---|---|
Status: | new → closed |
comment:5 by , 7 years ago
Replying to Sonu kumar:
This doesn't look to be a bug in Django. This is a more of MySQL query parser bug.
This is does not look like a query parser bug but a documented limitation of 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 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
Though neither mentions the use of an INNER JOIN
This doesn't look to be a bug in Django. This is a more of MySQL query parser bug.
Query generated by Django ORM
As we can the query generated by Django is totally valid but MySQL server has raise error