You can combine system time and valid time in a single table to use the features of both:
- Adding a system-time dimension to a table lets you track all changes made to the table, leaving a permanent, persistent history of rows within the table itself.
- Adding a valid-time dimension to a table allows the database to automatically adjust the valid-time period data as modifications to the table are made that affect the effective dates of the information contained in each row.
Because system time and valid time are independent dimensions any change to a bitemporal table affects each dimension independently, and the consequences to the table are a combination of the effects in cases that have been described for individual system-time and valid-time tables in Working With ANSI System-Time Tables and Working With ANSI Valid-Time Tables