repeating group

repeating group

(database)Any attribute that can have multiple valuesassociated with a single instance of some entity. Forexample, a book might have multiple authors.

Such a "-to-many" relationship might be represented in anunnormalised relational database as multiple author columnsin the book table or a single author(s) column containing astring which was a list of authors. Converting this to "firstnormal form" is the first step in database normalisation.Each author of the book would appear in a separate row alongwith the book's primary key. Later nomalisation stageswould move the book-author relationship into a separate tableto avoid repeating other book attibutes (e.g. title,publisher) for each author.