Research On Constraint Relational Model Of Non-Classical Relational Database In Query Optimization

The early classical relational database theory had played an important role in application. With the development of database theory, popularizing and reforming the classical relational database,we got the non-classical relational database theory.The constraint database theory has became a hot point of studying database.In the process of studying constraint database ,it was discovered that there was a kind of constraint,which had very broad range of applications in a variety of practical problems.This constraint could be added to the original database,and also could be added to the query results,we called it "dualistic relational constraint".It gives some dualistc relations between the value fields of the two of attributes on which each record of tables could only fetch the value of these dualistc relations.Of course ,it has wide application prospects in numerous fields.This dualistic relational constraint is existent widely,but in the classic relational database theory,all kings of "dependency"is neither related to this kind of constraint.In order to make database that containted a large number of dualistic relational constraints do more effient and optimized query, insertation, modification, and other operations.we need do seriously study for constriant's related issues,and also need further study to the realization of the dualistic constraint database model and oter related operations.In this paper it puts forword to bring in the ideas and related theories of dualistic constraint based on the ordinary relational database scheme,and to enlarge the simple RDS to define dualistc-constraint.By the way ,we can establish the new preliminary model on which we have expanded the theory of dualistic constraint.On this basis,we continue to discuss its realization of storage structure,and also the realization of DLL,DML manipulation and parts of relational algebra manipulation based on this new model.We can use relational database theory to implement Dualistic constraint database.An ordinary database becomes a dualistic constraint database when the dualistic constraint have stored in it as permanent data. In the latter chapter of this article, we will compare to the realization detail of other constraint database'laguage in order to expand the function of commom database language system.We will introduce the query implementation process of the new expanding database language .Query optimization is an important technology for the design and implementation of database system,and is also an important factor affecting database system performance.Dualistic constraint relational model has resolved the minimum problem of inequality conjunction query based on the arbitrary domain data in the database.Threrfore ,we bing in the minimum of theory of inequality conjunction query, and we will show how to achieve the better query optimizatiom.At the end ,we make an exposition of the sysyem structure of the new expanded model,and,accordingly it has given the experimental data,diagrams and instructions in order to further demonstrate a new model in the superiority of query optimization.Of course.there are still many questions and related aspects to be further explored in the paper,so we point out the directions at the end to work ahout the related fields in the future.