TIME IN DATABASES AND APPLICATIONS OF DATABASES

摘要

A database having data entries with attributes having values that can vary over system time (the time according to a computer clock) and also over valid time (the start time and end time of an interval during which the values of the attributes are true). All logical operations of updates and deletes of values are performed by insert operations that insert new entries into the database, so that all old entries that were present at previous systems still exist and still include their previously-assigned start times and end times for the value of the attribute.