A database management system is provided for protecting data from being malicious update or deleted. The system is arranged to hold as a table attribute an insert-only attribute and a row deletion prohibition period, and as an access right attribute a row insertion date and time holding column name and to specify a row insertion date and time when a row was inserted, for disabling said date and time data. When requesting a table data update or a row deletion, the table attribute and the row insertion date and time are checked for preventing the malicious update and deletion.