Access control in a relational data base management system by query modification

This work describes the access control system being implemented in INGRES (l__N_Nteractive Graphics and REtrieval S~stem). The scheme can be applied to any relational data base management system and has several advantages over other suggested schemes. These include: a) implementation ease b) small execution time overhead c) powerful and flexible controls d) conceptual simplicity The basic idea utilized is that a user interaction with the data base is modified to an alternate form which is guaranteed to have no access violations. This modification takes place in a high leve