We are used to living in a world in which information about an object is almost more important than the material object itself. When a new person is born, he immediately receives a name, inherits a surname and a middle name (directly according to the laws of object-oriented programming, be it wrong), they put on him the first document - a birth certificate, enter his whole background into various registries. As it grows and develops, archives of information about it will multiply and grow: medical history, documents in kindergarten, and then at school, a little later they will be interested in the military registration and enlistment office, and so on throughout life. You might think that all human life is dedicated only to the fact that various database management systems (DBMS) can fill their insatiable information insides. In some incomprehensible way, we continue to consider ourselves - man - the crown of nature, although animals seem to be often wiser than us.
Most people do not think much about all these tricks of information. They just live quietly themselves, occasionally fill out a wide variety of profiles, give consent to collect additional information about themselves (or do not even suspect about it). Someone processes all this information, its functions include database management, which includes a variety of information. This may be employees of banks, personnel services, employees of archives and many others. Even fewer people (programmers and system administrators) have to set up and maintain database management systems with their own hands, and sometimes even create them. The profession requires programmers to understand most clearly what information is, how to process it, and what programs are suitable for this.
When learning the profession of a programmer , among other things , the Access database management system is also studied. Strictly speaking, this DBMS is the most stupid, because it does not provide the real power of full-fledged servers: when several people work simultaneously with one database, fragments of information, or even entire tables, begin to block, with large amounts of data, malfunctions occur and so on. It remains a mystery why Access is included in the education system, because professional programmers will not work with it, and all the rest do not want to know how some database management systems differ from others. It would be better instead of Access, students were given skills in working with PostgreSQL and MySQL, along with explaining the differences between them. True, both of these DBMSs work only as servers, that is, to create a full-fledged database, you will also have to develop a client application - something that end users will work with. But all professional programming goes along this path, and you should not reinvent your own bike.
And what generally includes the concept of a professional database management system? Firstly, the ability to work with very large amounts of information (the electronic catalog of a large bookstore can have millions of descriptions, for each of which you can find out the price, the number of available copies and in which warehouses they are located); secondly, working with many users at the same time, each of whom receives relevant information (in other words, two sellers will not be able to sell a single copy of some rare book to different customers). The third parameter - information is protected from accidental damage in cases where its change began, but was not completed correctly. Hypothetically, one can imagine the following situation: a store receives payment by wire transfer, funds are debited from the customer’s account and then must be credited to the store’s account, but due to a failure the second part of the operation was not performed. A competent DBMS performs both parts of the operation within a single transaction, which is either fully confirmed (in the case when everything went smoothly) or is completely canceled (in case of any failure). At the buyer's level, this gives confidence that if funds are debited from his account, then they are guaranteed to be credited to the store’s account.