Reference Databases

SQLite does not support the SELECT ... FOR UPDATE syntax. Calling it will have no effect.

Reference Databases

MySQL and MariaDB do not support some options to the SELECT ... FOR UPDATE statement. If select_for_update() is used with an unsupported option, then a NotSupportedError is raised.

Reference QuerySet API reference

extra(select=None,where=None,params=None,tables=None,order_by=None,select_params=None) Sometimes, the Django query syntax by itself can’t easily express a complex WHERE clause. For these edge cases, Django provides the extra() QuerySet modifier — a hook for injecting specific clauses into the SQL generated by a QuerySet.

Reference QuerySet API reference

The resulting SQL of the above example would be: Note that the parentheses required by most database engines around subqueries are not required in Django’s select clauses.

Topic guide Multiple databases

You can select the database for a QuerySet at any point in the QuerySet “chain.” Call using() on the QuerySet to get another QuerySet that uses the specified database.

Topic guide Translation

If you want to select a language within a template, you can use the language template tag: While the first occurrence of “Welcome to our page” uses the current language, the second will always be in English.

Reference QuerySet API reference

Greater than. Example: SQL equivalent:

Reference Form fields

classChoiceField(**kwargs)[source] : - Default widget: Select - Empty value: '' (an empty string) - Normalizes to: A string. - Validates that the given value exists in the list of choices. - Error message keys: required, invalid_choice

Reference Form fields

classFilePathField(**kwargs)[source] : - Default widget: Select - Empty value: '' (an empty string) - Normalizes to: A string. - Validates that the selected choice exists in the list of choices. - Error message keys: required, invalid_choice

Reference Form fields

classModelChoiceField(**kwargs)[source] : - Default widget: Select - Empty value: None - Normalizes to: A model instance. - Validates that the given id exists in the queryset. - Error message keys: required, invalid_choice

Reference Widgets

classNullBooleanSelect[source] : - template_name: 'django/forms/widgets/select.html' - option_template_name: 'django/forms/widgets/select_option.html'

Reference Widgets

classSelectMultiple[source] : - template_name: 'django/forms/widgets/select.html' - option_template_name: 'django/forms/widgets/select_option.html'

Reference Widgets

classCheckboxSelectMultiple[source] : - template_name: 'django/forms/widgets/checkbox_select.html' - option_template_name: 'django/forms/widgets/checkbox_option.html' Like RadioSelect, you can loop over the individual checkboxes for the widget’s choices.

Reference QuerySet API reference

Case-sensitive containment test. Example: SQL equivalent: (The exact SQL syntax varies for each database engine.) Note this will match the headline 'Lennon honored today' but not 'lennon honored today'.

Reference QuerySet API reference

Case-insensitive containment test. Example: SQL equivalent: (The exact SQL syntax varies for each database engine.) NOTE: When using the SQLite backend and non-ASCII strings, bear in mind the > database note about string comparisons.

Reference QuerySet API reference

Case-sensitive starts-with. Example: SQL equivalent: (The exact SQL syntax varies for each database engine.) SQLite doesn’t support case-sensitive LIKE statements; startswith acts like istartswith for SQLite.

Reference QuerySet API reference

Case-insensitive starts-with. Example: SQL equivalent: (The exact SQL syntax varies for each database engine.) NOTE: When using the SQLite backend and non-ASCII strings, bear in mind the > database note about string comparisons.

Reference QuerySet API reference

Case-sensitive ends-with. Example: SQL equivalent: (The exact SQL syntax varies for each database engine.) NOTE: SQLite doesn’t support case-sensitive LIKE statements; endswith > acts like iendswith for SQLite. Refer to the database note documentation for more.

Reference QuerySet API reference

Case-insensitive ends-with. Example: SQL equivalent: (The exact SQL syntax varies for each database engine.) NOTE: When using the SQLite backend and non-ASCII strings, bear in mind the > database note about string comparisons.

Reference Settings

NOTE: Added in version 6.1. Default: False The default blank choice label in Select widgets was changed from "---------" to django.db.models.fields.BLANK_CHOICE_LABEL. Set this transitional setting to True to revert to the previous label.