FW: Relational Database vs. Nonrelational

[Lynn Perry <clperry -at- WALLDATA -dot- COM>]

Colleen

One way that helped me understand the functionality of relational databases
is this: typically, relational databases use tables to track the
relationships of data in other tables. For example, say you have a table
that contains employee information: FirstName, LastName, DeptName, and
another table that contains Department information: DeptName, DeptManager,
AccountingCode. In the nonrelational world, DeptName would be stored
multiple times, potentially, for each employee in that department. If you
had 100 employees and the company reorganized and changed the name of the
department, you would have to update 100 records--which can result in data
integrity problems such as typos, not to mention the time required to
accomplish such a task.

In a relational database, another table tracks the DeptName-Employee
relationship, typically using numbers. So each DeptName has a unique number
assigned to it by the database management system (DBMS). Then, in the
Employee table, the DeptName is represented by that number. That way, when
the name changes, you only have to change it in the Department table and the
changes would be reflected automatically throughout any other table that
contains DeptName.

I should note that some nonrelational databases have programming that
performs the same function. The difference is that a programmer actually has
to write code for this. In relational databases, the DBMS performs the
function for you. That means that when you query for Employee information
from a relational database, the DBMS does the table lookup, gets DeptName,
and displays the result.

This is a relatively simple example, but it really helped me out. Hope it
helps you, too.  If you have other specific questions, feel free to contact
me offlist.

LyP
clperry -at- walldata -dot- com
My opinions do not necessarily reflect those of Wall Data Incorporated and
vice versa.

> ----------
> From:         Colleen Adams[SMTP:AdamsC -at- MEDISPAN -dot- COM]
> Sent:         May 14, 1998 7:04 a
> To:   TECHWR-L -at- LISTSERV -dot- OKSTATE -dot- EDU
> Subject:      Relational Database vs. Nonrelational
>
> Can anyone out there give me information on differences between a
> relational database vs. nonrelational?
>
> Colleen Adams
> External Documentation Manager
> First DataBank Medi-Span, Inc.
> Indianapolis, IN
> colleen_adams -at- medispan -dot- com
>
> ~
>
>