DATABASE CONTROLLING METHOD

PURPOSE: To improve efficiency in keeping the consistency of a cache and a database by permitting an envelope transaction to hold a cache lock, a hold lock and an obsolete lock as against an object inside the cache of a client. CONSTITUTION: The envelope transaction inside the client 15, for example, holds the cache lock (C lock), the hold lock (P lock) and the obsolete lock (0 lock) as against the object inside the cache of the client 15. The C lock means that a copy exists in the cache. The P lock is locked when intending to apply an exclusive lock (X lock) to data which is locked by the C lock. The 0 lock is locked when it is recognized that data with the P lock applied is changed. The transaction accesses to the database of the client 15 at last and aborts the lock when the 0 lock has been applied.