C# Login Form Example

To create a login form in C# that connects to a database, you will need to use a combination of C# code and SQL commands. Here are the general steps to create a login form that connects to a database:

Create a new C# Windows Forms project.
Design the form by adding textboxes for the username and password, and a button to submit the login information.
Add a reference to the ADO.NET data provider for the database you are using (e.g. MySQL, SQL Server, etc.)
Use ADO.NET to connect to the database and execute a SQL command to check if the entered username and password match any records in the database.
If a match is found, allow the user to proceed. If no match is found, display an error message.

You can also use ORM(Object-relational mapping) libraries like Entity Framework to connect to the database and perform CRUD operations.

It’s recommended that you use a parameterized query and hash the password before storing in the database.


using System;
using System.Data;
using MySql.Data.MySqlClient;
using System.Windows.Forms;

namespace LoginForm
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnLogin_Click(object sender, EventArgs e)
        {
            string connString = "Server=localhost;Database=mydb;Uid=root;Pwd=password;";

            using (MySqlConnection conn = new MySqlConnection(connString))
            {
                conn.Open();

                string sql = "SELECT COUNT(*) FROM users WHERE username=@username AND password=@password";
                MySqlCommand cmd = new MySqlCommand(sql, conn);
                cmd.Parameters.AddWithValue("@username", txtUsername.Text);
                cmd.Parameters.AddWithValue("@password", txtPassword.Text);

                int count = Convert.ToInt32(cmd.ExecuteScalar());
                if (count == 1)
                {
                    MessageBox.Show("Successful login");
                }
                else
                {
                    MessageBox.Show("Invalid username or password");
                }
            }
        }
    }
}

using System;

using System.Data;

using MySql.Data.MySqlClient;

using System.Windows.Forms;

namespace LoginForm

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

private void btnLogin_Click(object sender, EventArgs e)

{

string connString = "Server=localhost;Database=mydb;Uid=root;Pwd=password;";

using (MySqlConnection conn = new MySqlConnection(connString))

{

conn.Open();

string sql = "SELECT COUNT(*) FROM users WHERE username=@username AND password=@password";

MySqlCommand cmd = new MySqlCommand(sql, conn);

cmd.Parameters.AddWithValue("@username", txtUsername.Text);

cmd.Parameters.AddWithValue("@password", txtPassword.Text);

int count = Convert.ToInt32(cmd.ExecuteScalar());

if (count == 1)

{

MessageBox.Show("Successful login");

}

else

{

MessageBox.Show("Invalid username or password");

}

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