System and method for providing safe SQL-level access to a database

Claim 1

A distributed computer system, comprising: an information server, the information server including a database management system (DBMS) and a port for receiving and responding to SQL statements; at least one client computer, coupled by a communication path to the information server; the at least one client computer including database access means for sending SQL statements database queries to the DBMS in the information server; the database access means including a plurality of embedded constant strings, the plurality of embedded constant strings comprising pre-encrypted representations of a first subset of a predefined full set of SQL commands recognized as legal SQL commands by the DBMS in the information server; each of the SQL statements sent by the database access means to the DBMS in the information server including the pre-encrypted representation of one of the first subset of SQL commands; wherein the first subset does not contain a predefined set of excluded SQL commands that are contained in the predefined full set; and the information server including means for processing the received SQL statements, including means for decoding the pre-encrypted representation of a SQL command included in each of the SQL statements sent by the database access means in the at least one client computer, and means for rejecting any received SQL statements that do not include a pre-encrypted representation of a SQL command that can be decoded by the decoding means into a corresponding one of the legal SQL commands using a predefined decoding methodology; wherein the at least one client computer is unable to generate SQL statements containing representations of any SQL commands not included in the first subset that will be not be rejected by the information server.