Updating multiple rows in pl sql
Each foreign key you add will implicitly include all of its default orderings as well.
If a query doesn’t have an ordering specified, results are returned from the database in an unspecified order.
To put it simply: if you need to ask, you don’t need to use it. An expression may be a simple value, a reference to a field on the model (or any related models), or an aggregate expression (averages, sums, etc.) that has been computed over the objects that are related to the objects in the that is returned.
The aggregation functions that are provided by Django are described in Aggregation Functions below.
Annotations specified using keyword arguments will use the keyword as the alias for the annotation.
Anonymous arguments will have an alias generated for them based upon the name of the aggregate function and the model field that is being aggregated.
You can order by a field converted to lowercase with Warning Ordering is not a free operation.
Each field you add to the ordering incurs a cost to your database.
If you specify the fields, each dictionary will contain only the field keys/values for the fields you specify.If you generate a pickle using Django version N, there is no guarantee that pickle will be readable with Django version N 1.Pickles should not be used as part of a long-term archival strategy.If you don’t specify the fields, each dictionary will contain a key and value for every field in the database table.Example: It is useful when you know you’re only going to need values from a small number of the available fields and you won’t need the functionality of a model instance object.
That is, the name of the field, followed by a double underscore ( could return more items than you were working on to begin with - which is probably neither expected nor useful.