repeating group

repeating group

   <database> Any {attribute} that can have multiple values
   associated with a single instance of some {entity}.  For
   example, a book might have multiple authors.

   Such a "-to-many" relationship might be represented in an
   unnormalised {relational database} as multiple author columns
   in the book table or a single author(s) column containing a
   string which was a list of authors.  Converting this to "first
   normal form" is the first step in {database normalisation}.
   Each author of the book would appear in a separate {row} along
   with the book's {primary key}.  Later nomalisation stages
   would move the book-author relationship into a separate table
   to avoid repeating other book attibutes (e.g. title,
   publisher) for each author.

   (2005-07-28)