The goal of SQL development was to create a simple language that any user could use, even without programming experience.

Example of SQL construction:

SELECT region_code, name
FROM cities

In relational databases, data is placed in tables (table). Tables consist of records (rows), each having its own set of fields (columns) for each table. In our case, the cities table has the fields region_code and name.

SQL from different vendors: Microsoft SQL, Oracle, MySQL, PostgreSQL – has its own features. Here we will use the PostgreSQL dialect. In the future, I plan to make notes on the features of other dialects.