This paper presents the results of the research of the team SITE at the computer science laboratory center LORIA in Nancy, France, within the framework of the collaboration of the research team with NetLor-Cocept Enterprise. The aim of this research is to retro design databases so that they can be realized with new DBMS and queried on the Web. Our article will present first, using many examples, the problems of reverse engineering of databases in a context of query on the Web and also the design of data warehouse. In a second part we will clarify more in detail the algorithm of data mining that enables us to redesign databases. Finally we will clarify how we will design a set of tools that integrates the results of this research undertaken by our research team SITE