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Django Queryset

Subject : it-skills
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. These add custom "row-level" functionality to your objects. These act on a particular model instance.






2. 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






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






4. Operator for comparing two model instances for equality. Behind the scenes - it compares the primary key values of two models.






5. 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.






6. Returns a QuerySet that will automatically "follow" foreign-key relationships - selecting that additional related-object data when it executes its query. This is a performance booster which results in (sometimes much) larger queries but means later u






7. This gives your model metadata.






8. Lookup type that returns results with a case-sensitive start sequence.






9. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.






10. 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.






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






12. 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






13. If this option is True - Django will store empty values as NULL in the database. Default is False.






14. If you pickle a QuerySet - this will force all the results to be loaded into memory prior to pickling. When you unpickle a QuerySet - it contains the results at the moment it was pickled - rather than the results that are currently in the database.






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

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16. (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.






17. This query uses an F object to increment the pingback count for every entry in the blog.

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18. The value given in the absence of a specified value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created.






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






20. This field is added automatically - but this behavior can be overridden






21. a QuerySet can be sliced - using Python's array-slicing syntax.






22. Lookup type that finds a case-sensitive regular expression match.






23. A convenience method for constructing an object and saving it all in one step.






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






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






26. Lookup type that returns results that fall into an inclusive date range.






27. A Q object that asks for entries with a question value that start with 'Who' or do not have a publication date of 2005.

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






29. Here - you can't use add - create - or assignment (i.e. - beatles.members = [...]) to create relationships. You need to specify all the detail for the relationship required by the intermediate model.






30. This query updates all the headlines with pub_date in 2007 to read 'Everything is the same'.

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31. 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.






32. In this case - an intermediate model can have multiple foreign keys to the source model. Here - two foreign keys to the same model are permitted - but they will be treated as the two (different) sides of the many-to-many relation.






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






34. Conjuntion operator for Q objects.






35. These are specified as keyword arguments to the QuerySet methods filter() - exclude() and get(). These take the form field__lookuptype=value .






36. This query finds all entries with an id in the list [1 - 3 - 4]






37. When to run syncdb






38. The first element in this iterable is the value that will be stored in the database - the second element will be displayed by the admin interface - or in a ModelChoiceField.






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






40. Takes the ouput of one filter and uses it as input for another filter. This works because a refinement of a QuerySet is itself a QuerySet.






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






42. Lookup type that tests for inclusion in a case-sensitive fashion.






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






44. 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






45. Use this method to reverse the order in which a queryset's elements are returned. Calling this method a second time restores the ordering back to the normal direction.






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






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






48. restrictions on ________: (1) Your intermediate model must contain one - and only one - foreign key to the target model. (2) Your intermediate model must contain one - and only one - foreign key to the source model. (3) When defining a many-to-many r






49. The database that will be used if this query is executed now






50. Keyword shortcut for looking up an object by primary key.