Introduction to databases

We start with the basic concepts to know what a database is.

The databases were engineered thanks to the need of large companies to store huge amounts of information in a fast, simple and reliable way, and that in turn could access it at any time without having to go to rooms dedicated to filing documentation, as was done until recently.

When computer programs began to take off, data began to be stored in program files, which was more convenient, but they still had great difficulties when it came to wanting to modify records, structures, or simply search for information.

Databases were born at the end of the sixties. These databases store the data used by users, companies, etc. And the programs that use them do not have to worry about their maintenance or storage, so a change in the database does not have to affect the programs that use it in principle.

As a definition of a database, we understand that it is a set of interrelated and stored data without unnecessary redundancies, which serve the applications without being directly related to each other.

A database can be used by several applications and users. Every database must allow inserting, modifying and deleting data, so information of two types is stored in the databases:

• User data (data used by applications)
• System data (data that the database uses for its management. For example, data of the users who have access to the database)

Organization of a database

To consider an organized database, it must meet the following objectives:

• It has to be versatile: this means that, depending on the users or applications, they can do different things or treat the data in different ways.
• It has to respond with the appropriate speed to each application or company, attending to what is required.
• It has to have a redundancy index as low as possible.
• Have a high access capacity to save as much time as possible in carrying out queries.
• Having a high integrity index, this means that by having many users attacking the same database, there can be no data insertion failures, redundancy errors or slow updating.
• Of course they have to have a very high level of security and privacy since the data that can be stored in a database can be highly confidential or important. At this point the physical means of protection against fire, theft, etc. also enter.
• Finally, it must be possible to constantly update it so as not to leave the database outdated and useless. When we make a change in the physical organization of the data, it should not affect the programs, so it also has to have physical independence from the data. In the same way that it has to have complete logical independence with the data, this means that if we make changes to the logical structure of the data (adding new fields to a table) they must not affect the applications that use that data.