Handbook of Data Quality by Shazia Sadiq

Author:Shazia Sadiq
Language: eng
Format: epub
Publisher: Springer Berlin Heidelberg, Berlin, Heidelberg

4 Data Dependencies and Data Quality

In Sect. 2 we have considered techniques for data quality centered in classical ICs, such as functional dependencies and referential constraints. These constraints, however, are not always expressive enough to represent the relationships among values for different attributes in a table.

Let us consider the example in Fig. 7 of a database storing information of the staff working at a newspaper. There are several restrictions on the data that can be represented using classical constraints. For example, in table Staff we have two FDs: (Num → Name,Type,Street,City,Country,Zip) and (Zip,Country → City). We also have the inclusion dependency: (Journalist[Num] ⊆ Staff [num]. It is easy to check that the instance in Fig. 7 satisfies all these constraints.

Fig. 7The Newspaper database

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.