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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. 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.






2. 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






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






4. This gives your model metadata.






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. 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






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






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






9. 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.






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






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






12. 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.






13. Returns a copy of the current QuerySet (or QuerySet subclass you pass in). This can be useful in some situations where you might want to pass in either a model manager or a QuerySet and do further filtering on the result. You can safely call all() on






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






15. 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.






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

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






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






19. 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






20. 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)






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






22. This object encapsulates a collection of keyword arguments - with the keys being field lookup types. These objects can be combined using the & and | operators - as well as negated with the ~ operator.






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






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






25. 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.






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






27. Fields are specified by these






28. Lookup type that returns results in a given list.






29. 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.






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






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






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






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






34. 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.






35. 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






36. 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()






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






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






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






40. Lookup type that finds a case-insensitive regular expression match.






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 year match. Takes a four-digit year.






43. what the field _______ determines: (1) The database column type (e.g. INTEGER - VARCHAR); (2) The widget to use in Django's admin interface - if you care to use it (e.g. <input type="text"> - <select>); (3) The minimal validation requirements - used






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






45. Returns the object matching the given lookup parameters






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






48. 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.






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






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