1. A method for maintaining information regarding multiple instances of an activity, each instance having an active condition in which information about the instance is to be modified or an inactive condition in which information about the instance is not to be modified, the method comprising: creating a record in a first database table for each of the multiple instances in the active condition, each record containing a field for each of a plurality of data types, one or more of the fields in each active instance record having a value indicative of the active condition; assigning, for records of the multiple instances in the inactive condition, values to the one or more fields indicative of the inactive condition; deleting from the first table records of instances having values in the one or more fields indicative of the inactive condition; and creating, for records deleted from the first table, a corresponding record in a second database table.