The main problem: storage, accumulation and search information
The unit of information will be considered data (D).
D. - some fact or a formal description of the phenomena that deserve attention to be considered.
Terminal representation D. - numbers and symbols (bits).
The minimum semantic unit is a data element (ED).
The set of interrelated D - logical record (LZ).
A set of LZ of the same type is a file.
Until the 1970s, there was a close relationship between data and applications.
There was a problem of centralization D. The first databases arose.
A database is a collection of computer-designed data processing that serves to meet the needs of many users within one or more organizations.
The difference between the database and files is that the information is not hidden from the user.

DB properties:

1. Speed ​​- quick access to information.
2. Full availability - all database information is available to the user.
3. Flexibility - the ease of change and the ability to fulfill any requests.
4. Integrity - reducing data duplication, data management.

There are two management concepts for D (DD):

1. Software development for a common interface between all users and an integrated database - DBMS (DBMS). These DBMSs provide integrity and privacy, and work automatically.
2. Use of DBAs (DBA) - a person or group of persons who are engaged in managing the database.

The main tasks of the DBMS and DBA:

1. Ensuring the integrity of the database. Consistency D, control.
2. Ensuring secrecy and authorized access.
3. Synchronization.
4. Protection against failures and restore the database.

Levels of abstraction (UA) DBMS

A physical database is tied to a specific OS and consists of files, blocks, stacks, clusters, etc. - the level of the system programmer.
A conceptual model is an abstract mapping of a physical model.
The view is an abstract mapping of the conceptual model.
The conceptual model and presentation are the responsibility of the application programmer and administrator.
The conceptual model does not depend on a specific DBMS and OS.
The structure of D at a conceptual level is called a conceptual scheme (COP).

The main components of the COP:

1. Essence - elementary D subject area (personality, facts of the phenomena).
2. Attributes are elementary D describing entities.
3. Connections - an association between elementary D.

The developed COP should be described at a more abstract level, i.e. should be presented as a model (M).