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Is it possible to check how many rows were deleted by a query?
queryset = MyModel.object.filter(foo=bar)
queryset.delete()
deleted = ...
Or should I use transactions for that?
@transaction.commit_on_success
def delete_some_rows():
queryset = MyModel.object.filter(foo=bar)
deleted = queryset.count()
queryset.delete()
PHP + MySQL example:
mysql_query('DELETE FROM mytable WHERE id < 10');
printf("Records deleted: %d\n", mysql_affected_rows());
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Usage. SQL Server @@ROWCOUNT is a system variable that is used to return the number of rows that are affected by the last executed statement in the batch.
Deleting a row is the third way to modify a ResultSet object, and it is the simplest. All you do is move the cursor to the row you want to delete and then call the method deleteRow . For example, if you want to delete the fourth row in the ResultSet uprs , your code will look like this: uprs. absolute(4); uprs.
Data manipulation language (DML) statements set the @@ROWCOUNT value to the number of rows affected by the query and return that value to the client. The DML statements may not send any rows to the client.
In SQL Server, you can use the @@ROWCOUNT system function to return the number of rows affected by the last T-SQL statement. For example, if a query returns 4 rows, @@ROWCOUNT will return 4.
There are many situations where you want to know how many rows were deleted, for example if you do something based on how many rows were deleted. Checking it by performing a COUNT creates extra database load and is not atomic.
The queryset.delete() method immediately deletes the object and returns the number of objects deleted and a dictionary with the number of deletions per object type.
Check the docs for more details: https://docs.djangoproject.com/en/stable/topics/db/queries/#deleting-objects
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