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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. Returns the object matching the given lookup parameters






2. 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.






3. 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.






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






5. 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






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






7. 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.






8. 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






9. 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.






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






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






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






13. Performs an SQL update query for the specified fields - and returns the number of rows affected. This method is applied instantly and the only restriction on the QuerySet that is updated is that it can only update columns in the model's main table. F






14. A Manager method that returns a new QuerySet containing objects that match the given lookup parameters.






15. 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






16. 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.






17. A manager method that returns a new QuerySet containing objects that do not match the given lookup parameters.






18. Performs an SQL delete query on all rows in the QuerySet. This method is applied instantly. You cannot call this method on a QuerySet that has had a slice taken or can otherwise no longer be filtered.






19. (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.






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






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






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






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






24. Disjunction operator for Q objects.






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

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


26. 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.






27. 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.






28. When to run syncdb






29. 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.






30. 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.






31. 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.






32. 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.






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






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






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






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






37. In some complex data-modeling situations - your models might contain a lot of fields - some of which could contain a lot of data (for example - text fields) - or require expensive processing to convert them to Python objects. If you are using the res






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






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






40. If True - the table does not permit duplicate values for this field.






41. 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.






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






43. 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






44. 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.






45. 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.






46. Lookup type for date/datetime fields that finds a 'day of the week' match.






47. 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.






48. Lookup type that returns results less than or equal to a given value.






49. This query finds all entries between a start date of start_date and an end date of end_date.






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






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