1. A non-transitory computer-readable storage medium containing a program for searching fields of a data repository using multiple levels of term expansion which, when executed, causes one or more computer processors to perform operations comprising: receiving, from a user, a relational database query containing a plurality of conditions, wherein at least one condition is a condition for searching at least one field of the data repository, wherein the at least one condition includes at least one base search term providing a keyword to search for in an unstructured text field of the data repository; providing an interface allowing a user to specify a level of expansion associated with the base search term, the level of expansion selected from the defined plurality of levels of expansions ranging from a lowest level of expansion to a highest level of expansion; determining one or more parameters specifying at least a credential associated with the user and a role associated with the user; providing a plurality of sets of expanded search terms for the base search term, each set corresponding to a different level of expansion of the plurality of levels of expansions, and each set comprising all expanded search terms from any lower level of expansion; obtaining the level of expansion associated with the base search term; obtaining, based on the base search term, the associated level of expansion, and the one or more parameters, one or more expanded search terms, wherein obtaining the one or more expanded search terms comprises selecting a set of expanded search terms from the plurality of sets of expanded search terms; and prior to executing the relational database query, modifying the relational database query to contain one or more additional conditions, wherein each additional condition includes one of the one or more expanded search terms.