Databases are used when the quantity and importance of the information are typical of organizations of a certain importance. In this case, archives, a summary of whose main functions can be found in this post, are no longer useful for storing data, and tools such as Database Management Systems (DBMS) are used, which allow the management of complex databases.

In short, a database is a complete collection of archived data. A DBMS is Instead, it is the set of databases, programs, and procedures used to access the data collection.

Characteristics of DBMSs

The main characteristics of DBMSs are the following:

• Integration. There is a single set of data and many programs that can operate on it, even simultaneously. Integration limits redundancy and eliminates inconsistencies. A database is precisely an integrated set of data that is stored without redundancy and is independent of the applications that use it.
• Integrity. The database management system ensures that data is inserted or modified while respecting the data constraints. In archive management, however, each application had to implement procedures to verify that the entered data respected the constraints defined on the data itself.
• Logical independence. The data is defined independently of the procedures that manage it. This means that following a modification to the database (for example, an extension of the portion of reality considered), there is often no need to modify the applications.
• Physical independence. The data is structured independently of its physical implementation, which primarily concerns the access methods, the way bits are stored in the computer's memory, or the distribution of data across multiple nodes in a network.
• Security. The database management system ensures that data is accessed only by authorized users.

In light of the above, we can provide a more complete definition. A database is a structured set of permanent data, grouped by type and meaning into interrelated structures, organized with limited redundancy, and used by different applications in a controlled and protected environment.

Users of a DBMS

Users of a DBMS can be both professional users and end users. They can be identified as follows:

• end users: these are users who interact with the database using application programs designed for this purpose;
• advanced users: these are users who can operate the database using native languages, therefore even without using the intended application programs.
• administrative users: these are professional users entrusted with the task of administering the database, creating users who can access the database, managing data access rights for each individual user, and modifying the database if necessary.
• programmers: these are users who develop software applications that interface with the database.

DBMS Languages

The user interacts with the database management system through specific Languages:

• Data Definition Language (DDL) is the language for defining the structure of data and the relationships between them;
• Data Manipulation Language (DML) is the language for manipulating the database by inserting, deleting, or modifying records;
• Query Language (QL) is the language that allows you to query the database to extract information.