Topic 7. ADO.NET database access: relational database and SQL fundamentals

Goal: become familiar with the relational data model, the PostgreSQL DBMS, and the psql and DataGrip tools; learn to design a normalized database schema, create tables with constraints, and write SQL queries with joins and grouping; master database access from C# through ADO.NET and Npgsql: parameterized commands, reading results, transactions, and displaying data in a DataGridView.

Lecture contents

1. The relational model and PostgreSQL — Databases and the relational model · Database design · The PostgreSQL DBMS and tools
2. SQL: tables and queries — Creating tables: DDL · Modifying and querying data
3. ADO.NET architecture and commands — ADO.NET architecture · Executing commands
4. Parameters, transactions, and DataGridView — SQL injection and parameterized queries · Transactions · Disconnected mode and DataGridView
5. Common mistakes — Common mistakes

Practice and review

• Practice — 3 worked examples with complete code and output
• Tasks — 30 variants, each with tasks at three difficulty levels
• Summary — conclusions, self-check questions, and useful links