Optional XML in a relational database, does the 1th part require null values?

Planning XML elements in a database and ignoring null values

Introduction: Optional XML elements, such as online forms, are very special because they can be selectively present in XML files. It is difficult to represent such optional elements in programming languages and databases. In many cases, empty optional elements are represented by inserting null values into the database, but it can be difficult to retrieve null XML values from the database. This article found a convenient way to handle optional XML elements that do not require data overloading or insertion of NULL or other tagged values.

As the cost of storage equipment increases, people no longer need to delete data. There is a growing volume of data, and there is a need for data management as no technology is truly free (including open source technology). The problem of data volume proliferation is just beginning to affect mainstream users, but for large data service providers, the problem has been a perennial disease. This article explores the management of XML data in relational data management.

Data management involves specialized technologies in a variety of areas, such as backup and recovery, database design, and service provider selection. Should backups be performed on a daily basis? What methods should be taken to design the database? Should you use a natural key or an application-generated primary key? For a service provider, should local or remote storage be performed on the data?

Although these issues are important, you will explore a very specific problem-a problem that can seriously affect data design, data retrieval, and client code management. The problem is to represent the optional XML element in the relational database. You will see that the solution that is used to model the optional XML element will have a far-reaching impact.

Road Map

This article introduces a number of techniques. To show the topic clearly, here's what we're going to discuss:

A brief review of XSD and XML

Builds XML and Java™ connections through Java architecture for XML Binding (JAXB)

Simple engine for publishing Java class data

Database entity classes

Resolving problems with optional XML data

Start with some data definitions first.