Research on the constraint restricts problem in the transition from SQL to XQuery

XML had already became the de facto standard of data exchange on Internet, many people had carried out a correlative study on the exchange between XML document and data with other forms, including transiting from SQL to corresponding XQuery query sentence, right away, the problem of constraint restricts between data was not resolved fairly well. In this essay a solution was brought out by increasing corresponding elements into the mapping dictionary, and also adding some corresponding processes.