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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. 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






2. 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.






3. Lookup type that corresponds to a boolean full-text search - taking advantage of full-text indexing. This is like contains but is significantly faster due to full-text indexing.






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






5. Evaluation happens upon use the "step" parameter of slice syntax - the first time you iterate over it - when pickling or caching results - upon calling repr() - upon calling len() - upon calling list() - upon calling bool()






6. This method immediately deletes the object and has no return value.






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






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






9. 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.






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






11. Fields are specified by these






12. 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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13. Evaluates the QuerySet (by performing the query) and returns an iterator over the results. A QuerySet typically caches its results internally so that repeated evaluations do not result in additional queries; this method will instead read results dire






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






15. Lookup type that yields an "exact" match. If you don't provide a lookup type -- that is - if your keyword argument doesn't contain a double underscore -- the lookup type is assumed to be of this sort.






16. 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.






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

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18. An iterable (e.g. - a list or tuple) of 2-tuples to use as options for this field. If this is given - Django's admin will use a select box instead of the standard text field and will limit options to those given.






19. 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






20. 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






21. 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.






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






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






24. 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






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






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






27. Defined by a ManyToManyField. You use it just like any other Field type: by including it as a class attribute of your model.






28. Returns an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.






29. Returns the most recent object in the table - by date - using the field_name provided as the date field.






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






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






32. If True - this field is the primary key for the model.






33. Exception raised by get(**kwargs) if more than one item matches the query.






34. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12






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






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






37. Returns the object matching the given lookup parameters






38. Accomplish this by using the field name of related fields across models - separated by double underscores - until you get to the field you want. For example - to get all Entry objects with a Blog whose name is 'Beatles Blog': Entry.objects.filter(blo






39. 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.






40. Extra text to be displayed under the field on the object's admin form to provide assistance to users. It's useful for documentation even if your object doesn't have an admin form.






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






42. This gives your model metadata.






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






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






46. (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.






47. 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.






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






49. This model method saves a model instance to the database. This method has no return value.






50. Returns an EmptyQuerySet -- a QuerySet that always evaluates to an empty list. This can be used in cases where you know that you should return an empty result set and your caller is expecting a QuerySet object (instead of returning an empty list - fo