CODEWITHSUNDEEP
sqldjangoormdjango-orm
Roman
Roman

Reputation: 35

Update statement in Django ORM

How to implement sql statement

update table1 
set field1 = field2

using Django ORM.

Upvotes: 1

Views: 1930

Answers (2)

neverwalkaloner
neverwalkaloner

Reputation: 47374

You can use update() with F expression:

from django.db.models import F
Table1.objects.update(field1=F('field2'))

Upvotes: 3

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 477684

Given you have a mode Table1 with the two fields, you can do this with:

Table1.objects.update(field1=F('field2'))

We here use a F-expression such that we reference to the field, not the value 'field2'. The statement with F(..) would result in setting all columns to the string 'field2' (given of course that is even possible, since field1 has to be able to store text data).

With Table1.objects we obtain access to the queryset of Table1 with (if not further specified) all objects. Note that we do not load these in memory. It is used to construct a query.

With .update(..) we can then update data in the rows that correspond to the queryset (here all rows, but we could have filtered as well).

Like said before, we can not simply pass 'field2' as a value. Since the ORM interprets this to setting field1 of all rows to the string 'field2'. We use an F-expression to reference to the column.

Upvotes: 2

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