A system to controls access to a database, including: an acquiring section which acquires an access program including a plurality of database access instructions; a detecting section which detects a plurality of different tables in the database that are accessed by the plurality of access instructions; a join control section which executes a join instruction prior to the execution of the access instructions, the join instruction obtaining a result table from the database by combining the plurality of different tables detected; and a conversion control section which executes a conversion instruction prior to the execution of the plurality of access instructions, the conversion instruction extracting records from the result table for the access instructions and converting the records into the form of a structure accessible for the plurality of access instructions.