A system and method for improving access efficiency in a database. The database stores values of a plurality of keys associated with the respective keys. The system of the invention executes a plurality of transactions on the database, and acquires and records a referenced value which is a value of a key referenced in a corresponding transaction from the database according to the execution of each of the transactions. Then, according to commit requests of the plurality of transactions, the system requests a reply of a resultant table including an arrangement of judgment results obtained by judging whether the value of the key stored in the database is maintained as the referenced value without change made by another transaction for the respective transactions. The system further judges whether each transaction is successful, based on the resultant table sent back and commits only transactions judged to be successful.