Re: Atomic Structures

From: vldm10 <vldm10_at_yahoo.com>
Date: Thu, 7 Jan 2016 19:58:34 -0800 (PST)
Message-ID: <36bb9283-98c1-46b1-a417-38e26607ee18_at_googlegroups.com>

In this post will be given a brief analysis of the Sixth normal form (6NF). How emerged 6NF? Let's consider the following example: Let's given relvar R {Key, Attribute1, Attribute2, Attribute3, Attribute4, DateFrom} and the following values for this relvar:

Key, Attribute1, Attribute2, Attribute3, Attribute4, DateFrom

---

Key1 a11 a21 a31 a41 d1

                       ...

Let us assume that the above shown relvar R is in 5NF. But despite the fact that relvar R is in 5NF, there is still a serious problem. In this example, the problem is the date "DateFrom". In this example, we do not know exactly on what is applied this date of change. Does "d1", that is date of the change, refers to a change in Attribute1 or in Attribute2 or in Attribute3 or in Attribute4. This problem can be solved by using the decomposition of R. Note that here we actually have a completely new organization of data, rather than a decomposition. Then we get the following atomic structure:

R1 {Key, Attribute1, DateFrom}
R2 {Key, Attribute2, DateFrom}
R3 {Key, Attribute3, DateFrom}
R4 {Key, Attribute4, DateFrom}

For example:

    Key Attribute2 DateFrom

---

    Key1,     a21,       d1
              ...

Now we know precisely that the changes occurred in the entity that is specified with Key1, on the attribute "Attribute2" and on date = "d1".

With this completely new organization of data, we have the new theory, which is much stronger in terms of a much wider range of application, as well as in solving more complex problems.

This example shows that it is necessary to do decomposition of the data structures in the atomic structures.

There are a number of cases which require the decomposition of data structures in the atomic structures. For example instead of DateFrom can be interval "DateFrom-DateTo". Instead DateFrom can be Bitemporal date "etc.

But 6NF does not provide a solution with which we can make the decomposition of data structures in the atomic structures. Authors of 6NF only provide the name for the atomic structures. This name is 6NF.

Vladimir Odrljin Received on Fri Jan 08 2016 - 04:58:34 CET