A method to perform the insertion, deletion and updating of data in table-format data quickly and appropriately. A CPU 12 accepts a record number as a subscript, generates a subscript conversion array for giving an offset value corresponding to the range of the subscript in question, identifies the insertion position which indicates the position of the field value to be inserted, and, in the subscript conversion array, gives an offset value that defines the range of the corresponding subscript and also identifies the end of the array, and in the subscript conversion array, gives an offset value that increments the corresponding range of subscripts and also decrements the accepted subscript, and places the field value to be inserted at the stipulated end position, such that an offset value according to the range of subscripts within the subscript conversion array is given as the subscript.