Help:Property constraints portal/Unique value

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distinct values constraint (Q21502410) specifies that values for this property should be unique across all of Wikidata, and no other item should have the same value in a statement for this property.

Almost all identifier properties have such a constraint, since an ISBN-13 (P212) or Freebase ID (P646) should uniquely identify an entity. Other examples include flag (P163) and anthem (P85).

Properties with this constraint usually also have single value constraint (Q19474404).

If no constraint scope (P4680) is specified, this constraint is only checked on the main value of a statement.

Possible actions[edit]

There are several possible ways to address a violation of this constraint:

  • It’s possible that the conflicting items are duplicates and should be merged.
  • It’s possible that the property value is erroneous on one of the conflicting items (e. g. a typo, accidentally transposed digits, etc.) and should be fixed.
  • It’s possible that the conflicting items are a rare, but legitimate exception to the constraint, and nothing should be done.

Parameters[edit]

This constraint does not have any parameters.

Example[edit]

property constraint
Normal rank distinct values constraint Arbcom ru editing.svg edit
▼ 0 reference
+ add reference
+ add value

Template[edit]

When the constraint is set to the property, the following template is automatically displayed in the property talk page. The template is created by Module:Constraints using Template:Constraint, invoked from Template:Property documentation. Translations are defined at Module:i18n/constraints.

Distinct values: this property likely contains a value that is different from all other items. (Help)
Exceptions are possible as rare values may exist.
List of this constraint violations: Database reports/Constraint violations/P236#Unique value, SPARQL (every item), SPARQL (by value), SPARQL (new)

Lists[edit]

Lists of properties which are set distinct values constraint.