Abstract: A database processing device executes concurrent processing in accessing a database through a plurality of independent terminal units. The database processing device, upon updating data stored in a record after reading out the data stored in the record in the database and correcting or altering the data through a specific terminal, confirms whether or not the data stored in the record has been updated by terminals, and executes updating only when the data has not been updated. The data stored in the record includes update control information for confirming whether or not the data has been updated by other terminals.

Abstract: A join operation processing system and a method of operating the system is usable in a distributed database management system including multiple local database management systems, computers employing distributed databases stored in the local database management systems, and a communication network for connecting said local database management systems and the computers. The join operation processing system can perform a join operation on a relational database. Each of the computers instructs prior computer to performing the join operation, and the database management system, managing relations associated with the join operation to read definitions so as to define said relations, reads the read definitions to thereby determine a process to process the join operation, and issues a request to the prescribed database management system to perform join operation processing based on the determination.