http://dl.acm.org/citation.cfm?id=810400
that a user interaction with the data base is modified to an alternate form which is guaranteed to have no access violations
modification takes place in a high level interaction language
user interacts with a data base through a high level query language … any such interaction is immediately modified into an interaction which contains no violations.
resulting interaction is compiled into a sequence of simpler interactions which are executed without further concern for access control.
frees the programmer from concern for how data structures are implemented and what algorithms are operating on stored data.