Time and Time Again: Versions and Episodes

There are many variations on version tables, but the variations make no difference to this discussion. In this particular case, version date is also the date the row was inserted, although in other variations, that is not always the case. There is no last update date, because versions are not physically updated. Instead, each logical update is carried out by copying the current version, applying the update to the copy and inserting the result as the new most current version. Finally, this particular variation on version tables also contains a delete flag, although this too is not present in all variations. When a delete is requested, the most current row is copied, its delete flag is changed from “N” to “Y,” and the new row inserted.