C# Academy · Lesson

Working with Databases

Connect to databases and perform CRUD operations using C#.

Lesson 4 of 510 steps

Working with Databases is a free C# Academy lesson on CoddyKit. This is lesson 4 of 5. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the C# Academy learning path, and your progress syncs across the web and the CoddyKit app. The C# Academy course includes 5 lessons in total.

Introduction to Databases

Working with Databases

Welcome to the next lesson! In this lesson, you’ll learn how to interact with databases in C#. We’ll cover establishing connections, executing queries, and managing data. Let’s get started!

What is a Database?

A database is an organized collection of data that can be accessed, managed, and updated. Databases are commonly used to store and retrieve information in applications.

Key Point: Relational databases, such as SQL Server and MySQL, organize data into tables with rows and columns.

Setting Up a Connection

To connect to a database, use the SqlConnection class from the System.Data.SqlClient namespace. Example:

Tip: Replace your_server and your_database with your actual server and database names.

using System;
using System.Data.SqlClient;

class Program {
    static void Main() {
        string connectionString = "Data Source=your_server;Initial Catalog=your_database;Integrated Security=True";

        using (SqlConnection connection = new SqlConnection(connectionString)) {
            connection.Open();
            Console.WriteLine("Database connection established.");
        }
    }
}

Executing SQL Commands

To execute SQL commands, use the SqlCommand class. Example:

Key Point: Use ExecuteNonQuery for commands that modify data (e.g., INSERT, UPDATE, DELETE).

using System;
using System.Data.SqlClient;

class Program {
    static void Main() {
        string connectionString = "Data Source=your_server;Initial Catalog=your_database;Integrated Security=True";

        using (SqlConnection connection = new SqlConnection(connectionString)) {
            connection.Open();

            string query = "INSERT INTO Users (Name, Age) VALUES ('Alice', 25)";
            SqlCommand command = new SqlCommand(query, connection);

            int rowsAffected = command.ExecuteNonQuery();
            Console.WriteLine($"{rowsAffected} row(s) inserted.");
        }
    }
}

Reading Data

To read data from a database, use the SqlDataReader class. Example:

Key Point: Always close the SqlDataReader after reading data.

using System;
using System.Data.SqlClient;

class Program {
    static void Main() {
        string connectionString = "your_connection_string_here";

        using (SqlConnection connection = new SqlConnection(connectionString)) {
            connection.Open();
            string query = "SELECT Id, Name FROM Users";

            using (SqlCommand command = new SqlCommand(query, connection)) {
                using (SqlDataReader reader = command.ExecuteReader()) {
                    while (reader.Read()) {
                        Console.WriteLine($"ID: {reader["Id"]}, Name: {reader["Name"]}");
                    }
                }
            }
        }
    }
}

Inserting Data

To insert data into a database, use the SqlCommand class with an INSERT query. Example:

Tip: Use parameters for dynamic values to prevent SQL injection.

using System;
using System.Data.SqlClient;

class Program {
    static void Main() {
        string connectionString = "your_connection_string_here";

        using (SqlConnection connection = new SqlConnection(connectionString)) {
            connection.Open();
            string query = "INSERT INTO Users (Name, Age) VALUES (@Name, @Age)";

            using (SqlCommand command = new SqlCommand(query, connection)) {
                command.Parameters.AddWithValue("@Name", "Alice");
                command.Parameters.AddWithValue("@Age", 25);
                int rowsAffected = command.ExecuteNonQuery();
                Console.WriteLine(rowsAffected + " row(s) inserted.");
            }
        }
    }
}

Updating and Deleting Data

Use the UPDATE and DELETE SQL commands to modify or remove data. Example:

using System;
using System.Data.SqlClient;

class Program {
    static void Main() {
        string connectionString = "your_connection_string_here";

        using (SqlConnection connection = new SqlConnection(connectionString)) {
            connection.Open();
            string updateQuery = "UPDATE Users SET Age = @Age WHERE Name = @Name";
            string deleteQuery = "DELETE FROM Users WHERE Name = @Name";

            using (SqlCommand command = new SqlCommand(updateQuery, connection)) {
                command.Parameters.AddWithValue("@Name", "Alice");
                command.Parameters.AddWithValue("@Age", 26);
                command.ExecuteNonQuery();
                Console.WriteLine("Data updated.");
            }

            using (SqlCommand command = new SqlCommand(deleteQuery, connection)) {
                command.Parameters.AddWithValue("@Name", "Alice");
                command.ExecuteNonQuery();
                Console.WriteLine("Data deleted.");
            }
        }
    }
}

Best Practices for Database Operations

Here are some best practices:

Always use parameterized queries to prevent SQL injection.
Close database connections promptly using the using statement.
Log database errors for debugging and monitoring purposes.

Tip: Use stored procedures for complex queries to enhance performance and maintainability.

Database Operations Recap

Great Job!

Congratulations! You’ve learned how to connect to a database, run queries, and manipulate data using C#. In the next lesson, we’ll explore LINQ for powerful and intuitive data queries. Let’s keep coding!

Working with Databases — illustration 10

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Frequently Asked Questions

Is the “Working with Databases” lesson free?

Yes — the full text of “Working with Databases” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the C# Academy course, upgrade to CoddyKit PRO. The C# Academy course includes 5 lessons in total.

What will I learn in “Working with Databases”?

Connect to databases and perform CRUD operations using C#. You practise C# Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start C# Academy?

No prior experience is required. C# Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 4 of 5.

How long does the “Working with Databases” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this C# Academy lesson?

Yes. Every C# Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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