Data Requirements

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A data requirement is a prescribed directive or consensual agreement that defines the content and/or structure that constitute high quality data instances and values. The following table contains different types of data requirements that can be expressed via the DQ-Constraint Library or the DQM-Vocabulary.

Types of Data Requirements

Data Quality Rule	Definition	Example	DQ-Constraint Lib for SPIN	DQM-Vocabulary
Mandatory Property and Literal Rules	Properties and their literals become mandatory, if the data is required for the task at hand.	The properties indicating the geographical coordinates must exist and have values for all instances of the class foo:Location to be able to navigate to each location.	dqc:MissingElementConstraints dqc:FunctionalDependentEmptyValueAll	dqm:PropertyCompletenessRule dqm:ConditionalPropertyCompletenessRule
Syntactic Rules	Syntactic rules define the type of characters and/or the pattern of literal values.	Literal values for the property foo:country-name must only contain letters.	dqc:SyntaxConstraints	dqm:SyntaxRule dqm:ConditionalSyntaxRule
Functional Dependency Rules	Functional dependencies are dependencies between the values of two or more different properties.	The literal value for foo:city is always dependent to the literal value for foo:country, since certain city names only exist in certain countries.	dqc:FunctionalDependencyConstraints	dqm:FuncDepValueRule dqm:FuncDepReferenceRule dqm:CustomRequirement
Legal Value Rules	Legal value rules are the explicit definition of the allowed values for a certain property.	The property foo:gender must only contain the values “male”, “female”, “m”, or “f”.	dqc:LegalValueConstraints	dqm:LegalValueRule
Legal Value Range Rules	Legal value range rules are the explicit definition of the allowed value range for properties holding numerical values. A value range contains an upper and/or lower limit.	The property foo:population must only contain values greater than zero.	dqc:ValueRangeConstraints	dqm:LegalValueRangeRule
Illegal Value Rules	Illegal value rules are the explicit definition of the values that may not be assigned to a certain property.	The property foo:gender may never contain the value “mail”.	dqc:LegalValueConstraints	dqm:IllegalValueRule
Illegal Value Range Rules	Illegal value range rules are the explicit definition of prohibited value ranges for properties holding numerical values. A value range contains an upper and/or lower limit.	The property foo:population must not contain values less than one.	dqc:ValueRangeConstraints	dqm:IllegalValueRangeRule
Unique Value Rules	Unique value rules define properties that may contain each literal value not more than once within a defined collection of values.	Each value for property foo:ISBN in instances of class foo:Book may not occur more than once.	dqc:UniquenessConstraints	dqm:UniqueValueRule
Outdated Value Rules	Outdated value rules are rules that identify instances that represent an outdated state of the corresponding real world entity.	Instances of the class foo:Offer are outdated, if its value for foo:validThrough is elder than the current date and time.	Not covered yet	dqm:UpdateRule dqm:ExpiryRule
Duplicate Instance Rules			Not covered yet	dqm:DuplicateInstanceRule