Re: [xml-dev] Equivalence of hierarchical and flat data formats

[Michael Kay <mike@saxonica.com>]

I don’t understand. The following flat data format uses primary/foreign keys to implement nesting:

In relational database normalization, a one-to-many relationship like book-has-author is usually represented by adding a primary key to the "one" end (book) and a foreign key to the "many" end (author). The problem then is how to represent the fact that there is a defined ordering to the authors of a book; and there's a variety of ways of handling this.

You've completely ignored normalization here - which is your prerogative, but it makes it meaningless to talk about primary and foreign keys.

Actually of course the book-has-author relationship is many-to-many, which creates another raft of issues.

Michael Kay

Saxonica

 

BookList.dat
Compilers Principles, Techniques, Tools               AUT01  Addison-Wesley               1986 
Introduction to Compiling Techniques               AUT02  McGraw-Hill      1996 
Economic Facts and Fallacies      AUT03               Basic Books        2011 
Economics in One Lesson             AUT04               Harper & Brothers           1946 

AuthorsList.dat
AUT01   Alfred V. Aho, Ravi Sethi, Jeffrey Ullman
AUT02   J. P. Bennett
AUT03   Thomas Sowell 
AUT04   Henry Hazlitt

 

Suppose I want to update the list of authors. Specifically, I want to add “John Doe” to the beginning of the AUT01 author list:

 

AUT01   John Doe, Alfred V. Aho, Ravi Sethi, Jeffrey Ullman

 

That update operation seems pretty straightforward to me. What is the issue that I’m not seeing?

 

/Roger