How to Connect to a SQL Database in C# Using ADO.NET

Connecting to a SQL database in C# is easier than you think, and thanks to ADO.NET, you can do it with just a few lines of code.

Whether you're building a robust enterprise app or just tinkering with databases for fun, understanding how to make this connection is essential. Let’s break it down!

Step 1: Install the Required Package

First things first, make sure you have the System.Data.SqlClient namespace available.

This is built into .NET Framework, but if you're using .NET Core or later, you should install the Microsoft.Data.SqlClient package via NuGet:

Install-Package Microsoft.Data.SqlClient

Step 2: Define Your Connection String

A connection string contains all the necessary information to connect to your database. Here’s an example of a basic connection string for SQL Server:

string connectionString = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;";

Server: The name of your SQL Server instance (e.g., localhost, 127.0.0.1, or a remote server).
Database: The name of the database you want to connect to.
User Id & Password: Your SQL Server credentials (if using SQL authentication). If you’re using Windows Authentication, replace these with Integrated Security=True;.

Step 3: Create the Connection

Now, let’s connect to the database using SqlConnection:

using System;
using System.Data.SqlClient;

class Program
{
    static void Main()
    {
        string connectionString = "Server=myServer;Database=myDB;User Id=myUser;Password=myPass;";
        
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            try
            {
                connection.Open();
                Console.WriteLine("Connection successful!");
            }
            catch (Exception ex)
            {
                Console.WriteLine("Connection failed: " + ex.Message);
            }
        }
    }
}

Breaking It Down:

We wrap our SqlConnection in a using block to ensure proper disposal after use.
connection.Open(); establishes the connection.
We catch any errors to avoid app crashes (always a good practice).

Step 4: Execute a Simple Query

Now that we’re connected, let’s run a basic SQL query:

using (SqlCommand command = new SqlCommand("SELECT TOP 5 * FROM Users", connection))
{
    using (SqlDataReader reader = command.ExecuteReader())
    {
        while (reader.Read())
        {
            Console.WriteLine($"User: {reader["Name"]}, Email: {reader["Email"]}");
        }
    }
}

What’s Happening Here?

We use SqlCommand to define our query.
ExecuteReader() fetches the data.
We iterate through the SqlDataReader to display the results.

Wrapping Up

And there you have it! You’ve successfully connected to a SQL database in C# using ADO.NET. Now you can run queries, fetch data, and build amazing database-driven applications.

Feeling adventurous? Try inserting, updating, or deleting records using ExecuteNonQuery(). Happy coding! 🚀

144

March 17 2025

How to Properly Close a SqlDataReader in C#?

Closing a SqlDataReader correctly prevents memory leaks, connection issues, and unclosed resources. Here’s the best way to do it.

Use 'using' to Auto-Close

Using using statements ensures SqlDataReader and SqlConnection are closed even if an exception occurs.

Example

using (SqlConnection conn = new SqlConnection(connectionString))
{
    conn.Open();
    using (SqlCommand cmd = new SqlCommand("SELECT * FROM Users", conn))
    using (SqlDataReader reader = cmd.ExecuteReader())
    {
        while (reader.Read())
        {
            Console.WriteLine(reader["Username"]);
        }
    } // ✅ Auto-closes reader here
} // ✅ Auto-closes connection here

This approach auto-closes resources when done and it is cleaner and less error-prone than manual closing.

⚡ Alternative: Manually Close in finally Block

If you need explicit control, you can manually close it inside a finally block.

SqlDataReader? reader = null;
try
{
    using SqlConnection conn = new SqlConnection(connectionString);
    conn.Open();
    using SqlCommand cmd = new SqlCommand("SELECT * FROM Users", conn);
    reader = cmd.ExecuteReader();

    while (reader.Read())
    {
        Console.WriteLine(reader["Username"]);
    }
}
finally
{
    reader?.Close();  // ✅ Closes reader if it was opened
}

This is slightly more error prone if you forget to add a finally block. But might make sense when you need to handle the reader separately from the command or connection.

161

12/22/2025

String Interpolation in C#: A Cleaner Way to Format Strings

String interpolation, introduced in C# 6.0, provides a more readable and concise way to format strings compared to traditional concatenation (+) or string.Format(). Instead of manually inserting variables or placeholders, you can use the $ symbol before a string to directly embed expressions inside brackets.

string name = "Walt";
string job = 'Software Engineer';

string message = $"Hello, my name is {name} and I am a {job}";
Console.WriteLine(message);

This would produce the final output of:

Hello, my name is Walt and I am a Software Engineer

String interpolation can also be chained together into a multiline string (@) for even cleaner more concise results:

string name = "Walt";
string html = $@"
    <div>
        <h1>Welcome, {name}!</h1>
    </div>";

146

12/22/2025

How do I add a comma to an integer in c#

In C#, you can format an integer with commas (thousands separator) using ToString with a format specifier.

int number = 1234567;
string formattedNumber = number.ToString("N0"); // "1,234,567"
Console.WriteLine(formattedNumber);

Explanation:

"N0": The "N" format specifier stands for Number, and "0" means no decimal places. The output depends on the culture settings, so in regions where , is the decimal separator, you might get 1.234.567.

Alternative:

You can also specify culture explicitly if you need a specific format:

using System.Globalization;

int number = 1234567;
string formattedNumber = number.ToString("N0", CultureInfo.InvariantCulture);
Console.WriteLine(formattedNumber); // "1,234,567"

411

12/22/2025

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How to Connect to a SQL Database in C# Using ADO.NET

Step 1: Install the Required Package

Step 2: Define Your Connection String

Step 3: Create the Connection

Breaking It Down:

Step 4: Execute a Simple Query

What’s Happening Here?

Wrapping Up

Related

Use 'using' to Auto-Close

⚡ Alternative: Manually Close in finally Block

Menu

Resources

Contact

Popular tags

How to Connect to a SQL Database in C# Using ADO.NET

Step 1: Install the Required Package

Step 2: Define Your Connection String

Step 3: Create the Connection

Breaking It Down:

Step 4: Execute a Simple Query

What’s Happening Here?

Wrapping Up

Related

Use 'using' to Auto-Close

⚡ Alternative: Manually Close in finally Block

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