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! 🚀

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Related

Storing passwords as plain text is dangerous. Instead, you should hash them using a strong, slow hashing algorithm like BCrypt, which includes built-in salting and resistance to brute-force attacks.

Step 1: Install BCrypt NuGet Package

Before using BCrypt, install the BCrypt.Net-Next package:

dotnet add package BCrypt.Net-Next

or via NuGet Package Manager:

Install-Package BCrypt.Net-Next

Step 2: Hash a Password

Use BCrypt.HashPassword() to securely hash a password before storing it:

using BCrypt.Net;

string password = "mySecurePassword123";
string hashedPassword = BCrypt.HashPassword(password);

Console.WriteLine(hashedPassword); // Output: $2a$12$...

Step 3: Verify a Password

To check a user's login attempt, use BCrypt.Verify():

bool isMatch = BCrypt.Verify("mySecurePassword123", hashedPassword);
Console.WriteLine(isMatch); // Output: True

Ensuring proper hashing should be at the top of your list when it comes to building authentication systems.

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Reading a file line by line is useful when handling large files without loading everything into memory at once.

✅ Best Practice: Use File.ReadLines() which is more memory efficient.

Example

foreach (string line in File.ReadLines("file.txt"))
{
    Console.WriteLine(line);
}

Why use ReadLines()?

Reads one line at a time, reducing overall memory usage. Ideal for large files (e.g., logs, CSVs).

Alternative: Use StreamReader (More Control)

For scenarios where you need custom processing while reading the contents of the file:

using (StreamReader reader = new StreamReader("file.txt"))
{
    string? line;
    while ((line = reader.ReadLine()) != null)
    {
        Console.WriteLine(line);
    }
}

Why use StreamReader?

Lets you handle exceptions, encoding, and buffering. Supports custom processing (e.g., search for a keyword while reading).

When to Use ReadAllLines()? If you need all lines at once, use:

string[] lines = File.ReadAllLines("file.txt");

Caution: Loads the entire file into memory—avoid for large files!

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Slow initial load times can drive users away from your React application. One powerful technique to improve performance is lazy loading - loading components only when they're needed.

Let's explore how to implement this in React.

The Problem with Eager Loading

By default, React bundles all your components together, forcing users to download everything upfront. This makes navigation much quicker and more streamlined once this initial download is complete.

However, depending on the size of your application, it could also create a long initial load time.

import HeavyComponent from './HeavyComponent';
import AnotherHeavyComponent from './AnotherHeavyComponent';

function App() {
  return (
    <div>
      {/* These components load even if user never sees them */}
      <HeavyComponent />
      <AnotherHeavyComponent />
    </div>
  );
}

React.lazy() to the Rescue

React.lazy() lets you defer loading components until they're actually needed:

import React, { lazy, Suspense } from 'react';

// Components are now loaded only when rendered
const HeavyComponent = lazy(() => import('./HeavyComponent'));
const AnotherHeavyComponent = lazy(() => import('./AnotherHeavyComponent'));

function App() {
  return (
    <div>
      <Suspense fallback={<div>Loading...</div>}>
        <HeavyComponent />
        <AnotherHeavyComponent />
      </Suspense>
    </div>
  );
}

Route-Based Lazy Loading

Combine with React Router for even better performance:

import React, { lazy, Suspense } from 'react';
import { BrowserRouter, Routes, Route } from 'react-router-dom';

const Home = lazy(() => import('./pages/Home'));
const Dashboard = lazy(() => import('./pages/Dashboard'));
const Settings = lazy(() => import('./pages/Settings'));

function App() {
  return (
    <BrowserRouter>
      <Suspense fallback={<div>Loading...</div>}>
        <Routes>
          <Route path="/" element={<Home />} />
          <Route path="/dashboard" element={<Dashboard />} />
          <Route path="/settings" element={<Settings />} />
        </Routes>
      </Suspense>
    </BrowserRouter>
  );
}

Implement these techniques in your React application today and watch your load times improve dramatically!

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