Basic concepts of databases

Before we start learning SQL, let's get acquainted with the basic concepts of databases. This will help us understand the scope of SQL and its runtime.

Database -
this is a set of data stored in a structured way.

In fact, this is just a repository of some information, nothing more. By themselves databases would not be of interest if there were no database management systems.

Database management system -
this is a set of language and software tools that provides access to data, allows you to create, change and delete them, provides data security, etc.
In simpler terms, a DBMS is a system that allows you to create databases and manipulate information from them.

The simplest scheme of working with a database:

The rating database

* Based on data db-engines.

  • Oracle
  • MySQL
  • Microsoft SQL Server
  • PostgreSQL
  • MongoDB
  • IBM Db2
  • Redis
  • Microsoft Access
  • Cassandra
  • SQLite

To sum up, it turns out that 7 out of 10rating databases are relational databases that are queried using SQL. These facts reveal its significance and ubiquity.

Well, let's not hesitate, continue the study.

Has a relational model
The syntax of the SQL query