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On 02/07/2012 05:20 PM, e-letter wrote:
On 07/02/2012, Jay Lozier<jslozier@gmail.com>  wrote:
IMHO, the real problem is that good data modeling is not usually taught
to users and unless they start working with databases they never learn
data modeling. Most books on using databases will, if briefly, discuss
the concepts of data modeling and database design. I do not remember any
book on a spreadsheet discussing it or even mentioning it.
Not sure if this beyond the scope of LO, but an explanation of how to
perform basic data modelling, design, planning would be very useful,
especially as a "suggested reading guide" before explaining the
features of base and calc.

AFAIK, a brief overview of data modeling is included in the Base guide (I think it is a hands on tutorial actually). Books on Access, MySQL, MSSQL Server, and MariaDB I have all have some information on data modeling because a good working knowledge is very important to proper database design.

Actually, for most people three key concepts are critical: determine what data you have and need, break up the data into logical groups, and design the data entry so that the data is entered only once. For your purposes, you may have more information available than you need or in some cases can easily generate the "data" from other data. The total price for an invoice could be generated other data included in the invoice, for example. Whether to include it depends on your needs and the details you will capture. How the data should be grouped depends on the type of data and how you need to use the data. You want table structures that allow entry of each piece of data without requiring used fields. On an invoice there are often multiple items but each invoice may a different number of items. Breaking the invoice into multiple tables; one for the basic invoice data and another for actual line items is recommended. The idea of enter once is critical, you want to reduce redundant data and eliminate as much data entry as possible, this makes locating, updating much easier.

The key modeling point is take a little time before starting to think about what you are doing and why you are doing it. You can use pen and paper or software tools and formal procedures to aid the process. For a simple project, could you write a few paragraphs clearly describing what you intend to do, how you intend to do it, and outline the data you plan to use? If, yes you have your solution outlined. The problem is that basic concept is simple but the execution can be difficult. I know often people will rush this step or skip it completely but it is very important.

There are massive tomes written about database design but do not lose sight that what you are doing is thinking about the problem and its solution before doing any detailed work on implementing it using the tools you have available.

--
Jay Lozier
jslozier@gmail.com


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