PURPOSE: To effectively utilize resources and to shorten processing time by deleting area for items not to be used or data not to be used by setting the record of a database at a variable length.

CONSTITUTION: A schemer 21 of a data definition part 2 defines the area of a basic part and the areas for items and additional parts for each record of data. A copy phrase of the data definition part 2 defines the item for each block of data inside the area of that additional part. A data storage part 1 stores the record of data based on the area of the original part, the areas of the items and the additional parts and the items. A memory extension part 3 extends the data respectively provided at the basic part and the additional part of the record preserved in the data storage part 1 onto a memory.