The need for the DBMS to support time dimension and the importance of it has been emphasized in a number of recent researches. To support time dimension means that the DBMS should maintain not only the current data but also the histories of those data. This thesis presents the efficient relational structure for storing the histories of data in a compact form and for providing the features with which the DBMS can support time dimension the methods to relax the difference between physical time and logical time, and the definitions of the operations in the 3-dimensional model are also presented. Last, it is shown that the operations defined in this thesis are enough to represent all derivable relations from the given 3 dimensional relations.