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Django ORM Ninja: Advanced Techniques for Developers
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Django ORM Ninja: Advanced Techniques for Developers

Django ORM Ninja: Advanced Techniques for Developers

1. Introduction to Django ORM
Introduction to the CourseIntroduction to the ORMStart a New ProjectInitialize a New Project
2. Models, datatypes, and fields
Defining The First ModelField Data TypesDefine Other ModelsMigrationsAdmin Interface
3. Queries
Create QueryRetrieve QueryLazy QueriesOrdering and SlicingUpdatingDeleting
4. Relations
Many-to-OneForeignKey ArgumentsOne-to-OneMany-to-Many
5. Complex Queries
Field LookupsQ and F ObjectsAggregationsAnnotationsMinimazing Database Hints
6. Advanced
Class MetaConstrainsTransactions BasicsUser Model

book
Ordering and Slicing

Slicing

Slicing, like Author.objects.all()[:1], retrieves a QuerySet limited to a specified range.

Remember that slicing on QuerySets, like [:1], is performed at the database level, so it's an efficient way to limit the number of results returned by a query.

Returns the first two objects (equivalent to LIMIT 2 in SQL).

Fetches the second and third objects from the table (akin to OFFSET 1 LIMIT 2 in SQL).

Ordering

To sort a QuerySet, use the order_by() method with the attribute name for ordering. Prepend '-' for descending order.

For ascending order ( SELECT * FROM Author ORDER BY first_name;).

For descending order ( SELECT * FROM Author ORDER BY first_name DESC;).

To define multiple ordering criteria in one order_by statement:

(SELECT * FROM Author ORDER BY first_name ASC, last_name DESC;).

1. What does the Django query Author.objects.all()[:1] return?
2. How does Django perform slicing on QuerySets like [:1]?
3. What is the SQL equivalent of Author.objects.all()[:2]?
4. How do you sort a QuerySet in ascending order by the 'first_name' field?
5. Which Django query sorts authors first by ascending 'first_name' and then by descending 'last_name'?
What does the Django query Author.objects.all()[:1] return?

What does the Django query Author.objects.all()[:1] return?

Виберіть правильну відповідь

How does Django perform slicing on QuerySets like [:1]?

How does Django perform slicing on QuerySets like [:1]?

Виберіть правильну відповідь

What is the SQL equivalent of Author.objects.all()[:2]?

What is the SQL equivalent of Author.objects.all()[:2]?

Виберіть правильну відповідь

How do you sort a QuerySet in ascending order by the 'first_name' field?

How do you sort a QuerySet in ascending order by the 'first_name' field?

Виберіть правильну відповідь

Which Django query sorts authors first by ascending 'first_name' and then by descending 'last_name'?

Which Django query sorts authors first by ascending 'first_name' and then by descending 'last_name'?

Виберіть правильну відповідь

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