To provide a database system, a data processing method and a database program for efficiently inserting data by recording the range of each group in a database.

A detail chart H1 is the chart of a database in which the data of one or more items are stored for every record. A title chart H0 is a preserving means for preserving range data showing the range of records for every group for the records stored in the detail chart H1, and sequenced for every group where the values of predetermined key items are made common, and the title chart H0 is defined as a second chart different from the detail chart H1. An adding part 2 is an adding means for adding new records to the database DB by executing processing to specify at least either the group or an inserting position in the group based on the above range data. An updating part 3 updates the range data based on the above addition.