| From the appearance of Web in 1991,it has been a huge globe information space. There is too much information and Web sites. Facing the information ocean, the users find that it is very difficult to discover useful information through Internet Explorer and usually spend much time but find little. It is an important and urgency task to efficiently retrieval Web information to help users find the documents subset in lots of documents information muster, which are related with the fixed queries. Meanwhile, how to use Web information query quickly and efficiently is also a fundamental to make full use of Web potentiality in all kinds of fields, such as digital library and e-commence.But we must note that information query is not the unique task about Web. Early in 1950',computers were used to storage and manage documents in library. After 30 years development, the information query showed to the world as an independent research field and there had been so many fruitful achievement on document content description, index model, matching strategy etc. The appearance of Web provided an experiment environment and application context, which people could never imagine before. Many Web information Retrieval systems arised, such as Yahoo! And Google. Meanwhile, the huge capacity, asynchromic, distributed and dynamical characters of Web bring new challenges to information query field, we must begin new research work based on the traditional information retrieval technology. The technologies of Web Query developing very fast gradually step from the search engine. With the development of Web, XML grows up to be hotspot that the research institutions and enterprises pursue and has been a general language used in Web data, which has the characteristic of structure, formalization, expansibility and concision. Meanwhile, The characteristic of this language's working on different platform permits that the developers can congregate and combine the data from all the usable resources and make them more valuable. The indexes are very important In XML Query. The expenses of estimating the XML query generally only consider CPU expense and I/O expense, while I/O expense largely depends on the statistical information in XML data, which relate with path directly recorded in the path index.Because XML can easily combine the structure data from different resource, it is possible to search different Databases, which are probably not related between these Databases, and makes the promise future and probability of resolving Web Data Mining. XML/RDF can explicitly describe the unite, structure and formalization of different sorts Web information sources, and it considers the objects of Web environment as resources and sets down unambiguous grammar and semantic, meanwhile it makes us research and develop new Web Mining technologies and use traditional mining algorithms and tools to carry out specific and multi-arrangement Data Mining, based on programming and structure data.Firstly, this paper comments on the characters of Web which bring many problems and opportunities to information query, then discusses the principles of traditional information technology and work mechanism of search engine and analyzes the shortcomings of traditional search engine. Meanwhile detailed comments on present Web query language. Lastly, mostly concerns on some new technology of Web Mining, which is higher lever in Web Query.This thesis has been divided into five parts. In part one, I mainly discuss the Web information characteristics of Web Database and note that the most important difference between the traditional database and Web retrieval system is that the data structure is stronger in traditional database, which contains more semantic. To some extent, the information retrieval technology is more suitable to deal with non-structure data, but the database is the best way to manage structure data. Generally, there are two ways to realize connect and application of Web Database system, one is to provide middle-ware which basically include CGI and AP...
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