Databases Reference
In-Depth Information
Here is the view which re-presents Current Projections. With
the suffix “Curr_Proj” standing for “current projections”, it looks
like this:
CREATE VIEW V_Policy_Curr_Proj
AS SELECT oid, eff_beg_dt, eff_end_dt, client, type, copay
FROM Policy_AV
WHERE asr_beg_dt
<¼
Now() AND asr_end_dt
>
Now()
AND eff_beg_dt
>
Now()
As we can see, effective time is explicitly represented in this
view, and so the view is a collection of uni-temporal versioned
data. As such, it has the unique identifier that all version tables
have—{oid
eff-end}, in which the two dates are not
merely two dates, but each the semantically complete represen-
tative of a PERIOD datatype.
The Current Projections dataset is the collection of all future
versions in an asserted version table that we currently assert as
making actionable statements. A simple example of a current
projection is a version that shows a change in a policy's copay
amount that will go into effect next month. The version exists
in current assertion time but in future effective time.
eff-beg
þ
þ
Pending History: Future Claims About the Past
The Pending History dataset consists of all those rows in an
asserted version table which lie in the assertion time future but
in the effective time past. Its subject matter is things as they used
to be. Its rows are claims which we are not yet willing to make
about what is now part of history. Pending History is a record
of what we may eventually be willing to say the past was like,
once we've got all our facts straight.
Here is the view which re-presents Pending History. With the
suffix “Pend_Hist” standing for “pending history”, it looks like
this:
what we used to claim
what we currently claim
what we will claim
what things
used to be like
what we will claim things
used to be like
what things
are like
what things
will be like
Figure 13.10 Pending History.
