1. A method of querying a database containing a plurality of data records for a population of patients, the data records including personal information relating to the patients and medical information relating to the patients, the method including the steps of: displaying a plurality of search criteria on a first portion of a display; responding to a user dragging and dropping a first search criteria onto a second portion of the display by displaying the first search criteria in a first position on the second portion of the display; responding to the user dragging a second search criteria to a second position in the second portion of the display, the second position being separated from the first position by a first distance in a first direction, by displaying a first indicator representing a first Boolean operational relationship between the first search criteria and the second search criteria; responding to the user dragging the second search criteria to a third position in the second portion of the display, the third position being separated from the first position by a second distance in the first direction, by displaying a second indicator representing a second Boolean operational relationship between the first search criteria and the second search criteria, the second Boolean operational relationship being different than the first Boolean operational relationship; responding to the user dropping the second search criteria into one of the second position and the third position by identifying data records from the plurality of data records that satisfy a query defined by the first search criteria, the second search criteria, and the Boolean operational relationship between the first search criteria and the second search criteria corresponding to the dropped position of the second search criteria; and identifying a group of patients corresponding to the identified data records that satisfy the query.