Analysis of a database

Introduction

When designing a software that interfaces with a database, either to desktop or Web interface, it is dedicated to a specific use rather than to another, you must always make a careful analysis to avoid having to deal with issues such as referential integrity, data redundancy, etc..

The purpose of this analysis is an important work: to achieve better optimization of the data and resources in anticipation of future deployments or changes to the database.

The purpose of this article is to put the reader to face in the future projects, starting with their right foot in the process of organizing information by having to deal with, or in a position to carry around a well-designed database, software, and leaner performance.

Who is the customer?

It 'a stupid question or too wide? Maybe, but you can start giving the mark-two responses:

1. I have to satisfy the customer;
2. to satisfy the customer ... is a client.

Case 1. Are you sure you have clear ideas about what you need? Sure you have considered all all all? Are you sure you do not have too much hurry?

If you have not asked these questions ... ponitele!

I just addressed to the reader in a very direct tone, avoiding the point, he turns that I can not and now I want to avoid answering the second case.

Case 2. The customer is not to satisfy the developer, but someone who may have a minimum of computer knowledge or not. If you have any knowledge can simplify our lives because "we speak the same language", or is it a pedantic that life tends to complicate the next. Or is a person who understands nothing but the computer knows what he wants (rare) or you can let us know. Or do not even know what he wants or is able to provide the necessary information.

Take this statement as a law: never take anything for granted, anyone who has the face! It 'better to be petulant, consider and reconsider everything, in order to avoid reaching conclusions that just because we try to meet or who are wrong for one reason or another.

I close this necessary brackets likely to give the reader understand that the most important thing is to have clear ideas, have a cauldron of information is not yet organized, in order to organize the best, as we shall see below.

Make a good analysis of a database

As mentioned in the SQL Guide for this site, rather than the various SQL based database (MS Access, MySQL, and so on) are not difficult to use. Sure, there are more or less complex products or intuitive, but that's not the point.

The point is to know what to do!

Tion and therefore assume that the reader have a minimum of cognition in terms of managing a relational database, SQL language and know the know how to use any DBMS product choice being irrelevant for the purposes of understanding this article.

What to do can be summarized in six points:

1. gather information to manage;
2. divide them into logical groups;
3. think well to division into tables and data types to be used;
4. think that "percentage" of redundancy you want to be;
5. assume a different structure;
6. turn off the computer, staring at the ceiling, to rethink the structure

This statement is both serious and humorous, although to a certain point: it is said that the first idea is the right one (this is the meaning of section 5) and it is better to notice before you start writing the management software "around" the database.

Example: database structure of a directory of companies

It is very popular on the Web in recent years the concept of directories, be it a directory to index, whether a directory to search for products, services, companies and so on.

Not being able to use up all the knowledge in this context related to a database to manage (the series going to infinity and beyond) we try to create a data structure to handle this type of service.

What should you do this service?

1. collect users;
2. managing geographic locations;
3. manage categories and subcategories;
4. handle the details, associating them with the points 1, 2 and 3;
5. include options such as paid subscriptions and so on.

In the paragraphs to follow will be described and commented on all the tables useful - from my point of view - to manage the application in question in this section. The data types are indicated, taking into account MS Access, the database system being easier to use, then the reader closer to understanding both less experienced than the most experienced, advanced user of DBMS.

With regard to the length of the field, I leave to the discretion of the reader to establish it. In some cases the lengths of the fields are required (eg tax code has 16 characters, the CAP has 5 and so on), while for other things like a name, a URL, I can recommend from 50 to 150 characters.

Fate vobis!

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