1. A method for performing an operation based on multidimensional data in a relational database, wherein the multidimensional data that is stored in the relational database includes a plurality of dimensions and at least one dimension of the plurality of dimensions includes a hierarchy having two or more levels of granularity, the method comprising the computer-implemented steps of: generating a query that defines a cube, the query including a first set of instructions to select a portion of said multidimensional data for inclusion in said cube and a second set of instructions to cause said cube to contain multidimensional data aggregated at each of said two or more levels of granularity of said at least one dimension; receiving a request for a first operation; based on the request, modifying the query to generate a modified query that includes a third set of instructions that represent the first operation; and submitting the modified query to a relational database engine to cause the first operation to be performed against the cube.