As per this link, this is the xml that maintains "BookStore" data.
I see that number of occurences of author are varying for any book.
xml's hierarchical representation of BookStore looks more meaningful/intuitive for me to visualise the data unlike relational table tuples. It is rather more difficult(kind of tweek) to map such hierarchical information in tables.
It is strange to see that real world(hierarchical) data(for example, SNMP MIBs of network devices or BookStore etc…) are mapped to tables of records in many commercial softwares. For me, it is not-intuitive(rather unnecessary skill) to convert such hierarchical data to tables, despite relational DB(like MSSQL) support massive/safe/multi-user/convenient/efficient/reliable unlike xml file format.
So, we are trying to fit hierarchical ordered data into table tuples which is an overhead. Do we have any commercial database that companies use to maintain schema in hierarchical fashion?
Note: am currently part of database course.
Best Answer
If you choose to maintain a hierarchy in a relational database, you need to look into the Nested Set design pattern. (See Wikipedia)
This model involves some programming, and it involves some overhead at insert or update time. The benefit comes at retrieval time. Retrieving the path or the subtree for any given node is easy and fast, when compared to the traditional approach, called Adjacency List.