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Django Queryset

Subject : it-skills
Instructions:
  • Answer 50 questions in 15 minutes.
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  • Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. If True - the table does not permit duplicate values for this field.






2. To activate your models






3. Lookup type that returns results greater than a given value.






4. Exception raised by get(**kwargs) if no items match the query.






5. This method is more or less the opposite of defer(). You call it with the fields that should not be deferred when retrieving a model. If you have a model where almost all the fields need to be deferred - using this method to specify the complementary






6. Lookup type for date/datetime fields that finds an exact year match. Takes a four-digit year.






7. This model type is useful if you only want to modify the Python-level behavior of a model - without changing the models fields in any way. This creates a stand-in for the original model. You can create - delete and update instances of this new model






8. This represents a collection of objects from your database. It can have zero - one or many filters.






9. Lookup type that returns results with a case-insensitive start sequence.






10. Sometimes - the Django query syntax by itself can't easily express a complex WHERE clause. For these edge cases - Django provides this QuerySet modifier -- a hook for injecting specific clauses into the SQL generated by a QuerySet.






11. This tells Django how to calculate the URL for an object. Django uses this in its admin interface - and any time it needs to figure out a URL for an object.






12. Returns a ValuesQuerySet -- a QuerySet that returns dictionaries when used as an iterable - rather than model-instance objects.






13. Lookup type that returns results less than a given value.






14. A Q object that encapsulates queries for entries with a question value that starts with 'What' in a case-insensitive fashion.


15. If this option is True - the field is allowed to be blank. Default is False.






16. This is a criterion that narrow down a QuerySet based on given parameters.






17. Takes a list of primary-key values and returns a dictionary mapping each primary-key value to an instance of the object with the given ID.






18. Adds to each object in the QuerySet with the provided list of aggregate values (averages - sums - etc) that have been computed over the objects that are related to the objects in the QuerySet. Each argument to this is content that will be added to ea






19. Defines a many-to-one relationship. ou use it just like any other Field type: by including it as a class attribute of your model.






20. This method returns tuples of values when iterated over. Each tuple contains the value from the respective field passed into the call to this method -- so the first item is the first field - etc.






21. Lookup type that yields a case-insensitive match.






22. Returns a dictionary of aggregate values (averages - sums - etc) calculated over the QuerySet. Each argument to this method specifies a value that will be included in the dictionary that is returned.






23. This method is for controlling which database the QuerySet will be evaluated against if you are using more than one database. The only argument this method takes is the alias of a database - as defined in DATABASES.






24. (1) These cannot be Python reserved words - because that would result in a Python syntax error. (2) These cannot contain more than one underscore in a row - due to the way Django's query lookup syntax works.






25. A QuerySet is iterable - and it executes its database query the first time you iterate over it.






26. These are "anything that's not a field" - such as ordering options (ordering) - database table name (db_table) - or human-readable singular and plural names (verbose_name and verbose_name_plural)






27. Lookup type that returns results with a case-sensitive end sequence.






28. This query deletes all Entry objects with a pub_date year of 2005.






29. This class type is useful when you just want to use the parent class to hold information that you don't want to have to type out for each child model. This class isn't going to ever be used in isolation. When it is used as a base class for other mode






30. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.






31. Negation operator for Q objects.






32. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.






33. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.






34. A Python "magic method" that returns a unicode "representation" of any object.






35. This model method is used for updating a ManyToManyField.






36. A manager method which returns a single object. If there are no results that match the query - this method will raise a DoesNotExist exception. If more than one item matches this query - the method will raise MultipleObjectsReturned.






37. Specifies the model that will be used to govern the many-to-many relationship. You can then put extra fields on the intermediate model. The intermediate model is associated with the ManyToManyField using this to point to the model that will act as an






38. This query finds all entries with an id greater than 4.






39. Lookup type that returns results with a case-insensitive end sequence.






40. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.






41. Used to get a QuerySet for a model. This is called 'objects' by default.






42. A convenience method for looking up an object with the given kwargs - creating one if necessary.






43. Returns a new QuerySet containing objects that match the given lookup parameters.






44. Defined by django.db.models.ForeignKey. You use it just like any other Field type: by including it as a class attribute of your model.






45. Returns True if the QuerySet contains any results - and False if not. This tries to perform the query in the simplest and fastest way possible - but it does execute nearly the same query. This means that calling this method on a queryset is faster th






46. Can be used to remove all many-to-many relationships for an instance






47. This style of inheritanc is useful when you're subclassing an existing model (perhaps something from another application entirely) and want each model to have its own database table. Here - each model in the hierarchy is a model all by itself.






48. Fields are specified by these






49. By default - results returned by a QuerySet are ordered by the ordering tuple given by the ordering option in the model's Meta. You can override this on a per-QuerySet basis by using the this method.






50. This sets a field to a particular value for all the objects in a QuerySet. You can only set non-relation fields and ForeignKey fields using this method.