FUNCTIONAL DEPENDENCIES IN XML

XML has become a standard for data representation and exchange on the Internet. The functional dependency is the most important part of the research on XML database normalization and there is already some research work on this topic. According to the types of existing complicated functional dependency constraint, the features of the data constraint are analyzed. A definition of XML functional dependency (XDF) is proposed which is based on a DTD path language. Compared with formal definitions already proposed, XFD proposed in this paper can express more XML dependencies, which makes it more suitable for further research work.