保持数据约束的关系数据库至XML文档的转换

XML已成为Internet上的技术趋势,在保留原有关系数据库的同时发展XML文档是目前的最佳选择,它需要在保持数据依赖约束基础上实现关系数据库与XML文档的转换.这一过程中,模式转换必须先于数据转换,因为现有的关系数据库通常是规范化的,重建XML文档树结构才能实现这一转换.为了达成此目的,首先依据已有的数据依赖约束将规范化的关系联合进一组表格,实现反向规范化,然后将这些联合表格映射为一组DOM,归并成XML文档树,根据用户选择的根结点,以及与它相连的结点形成一个期望的局部文档树,被选的XML文档树又映射为DTD格式的XML模式.这样就可以将联合表映射成一组DOM,并将其归并成单一DOM,最终转换成XML文档.

CONVERTING RELATIONAL DATABASE INTO XML DOCUMENTS WITH DATA CONSTRAINTS PRESERVATION

XML is recognized as the trend of technology on the Internet,and it's the best choice that developing new XML documents while running existing relational databases.But it needs converting relational databases into XML documents with constraints preservation.In the process,schema translation must be done before dataconversion.Since the existing relational databases are usually normalized,they have to be reconstructed into XML document tree structures.This can be accomplished through denormalization by joining the normalized relations into tables according to their data dependency constrains.The joined tables are mapped into DOMs,which are then integrated into XML document trees.The user specifies an XML document root with its relevant nodes to form a partitioned XML document tree to meet their requirements.The selected XML document tree is mapped into an XML schema in the form of DTD.We then load joined tables into DOMs,integrate them into a DOM,and transform it into an XML document.