The first part of the tutorial forms the basis for the basic course and contains a brief overview of the requirements and criteria for evaluating DBMS and databases, theoretical relational data model, basic SQL query language constructs, PostgreSQL database access organization, application design issues and major enhancements available in PostgreSQL.The second part, added in this edition contains material that will be useful to database and DBMS developers. It details storage structures, query execution and optimization methods, additional SQL capabilities, consistency and reliability tools. Software tools of database servers, tools of PostgreSQL functionality expansion, issues of creation of systems with replication, parallel and distributed database systems are considered.