1. A method of controlling access to a plurality of records stored in a database, the method comprising: performing the following steps using a computer system: receiving a request to perform a first operation on the plurality of records stored in the database; receiving an authentication identifier; retrieving a calculation expression associated with the requested first operation and with the received authentication identifier, wherein the calculation expression is based on at least one variable field of the plurality of records, wherein the plurality of records includes at least a first and second records, wherein the retrieved calculation expression is evaluated for the first and second records; retrieving a first current value from the at least one variable field of the first record; evaluating the retrieved calculation expression using the retrieved first current value from the at least one field of the first record; and retrieving a second current value from the at least one variable field of the second record; evaluating the retrieved calculation expression using the retrieved second current value from the at least one variable field of the second record; and granting or denying access to the first operation on the first and second records based on the evaluated calculation expression for the first and second records.