Databases Reference
In-Depth Information
Episode A
Episode C
Episode B
1
2
5
3
4
Jan
2010
Jan
2011
Jan
2012
Jan
2013
Jan
2014
Figure 10.3 Creating an Episode: After the Transaction.
Immediately prior to this transaction, the currently asserted
life history of policy P861 is as shown in
Figure 10.2
. After the
transaction is completed, that history will be the history of
the policy as asserted up to (but not including) August 2011.
The new currently asserted history of the policy will be as shown
in
Figure 10.3
.
Episode C, as we have labeled it, is a single-version episode.
Of course all episodes, when initially created, are single-version
episodes. Using the in-line notation introduced in Chapter 6,
this new episode looks like this:
P[P861[Jan11-Mar11][Aug11-9999][Jan11][C882, PPO, $30]
[Aug11]]
This example shows our business correcting a mistake. The
mistake was forgetting to record that policy P861 was in effect
for those two months until eight months after the fact. What
probably happened is that in August, the policy holder filed a
claim against the policy. The claim was rejected, the policy
holder complained, people in the company did some research,
the customer service representative apologized, the policy was
retroactively created and, finally, the claim was processed.
New episodes can be created proactively, before they go into
effect, just as easily as they can be created retroactively, after they
go into effect. But in the scenario shown here, that is not possible.
The reason is that Episode B is an open episode; it remains in
effect until further notice. Its version 4 has an effective end date
of 12/31/9999. Therefore, any attempt to proactively create a
new episode, i.e. to create an episode that began sometime after
August 2011, would violate temporal entity integrity.
Lengthening an Episode Backwards
In the previous example, the mistake our company made was
to fail to record that a policy was in effect until several months
after the fact. Another kind of mistake is to get the effective begin
date wrong. For example,
Figure 10.3
shows the first episode of
