public partial class LoginForm : Form
    {
        private const string connectionString = "ConnectionString"; 

public LoginForm()
{
    InitializeComponent();
}

private void btnLogin_Click(object sender, EventArgs e)
{
    string enteredUsername = txtUsername.Text;
    string enteredPassword = txtPassword.Text;

// Establish a connection to the database
using (SqlConnection connection = new SqlConnection(connectionString))
{
    try
    {
        connection.Open();

        // Prepare the SQL query to check the entered username and password against the table
        string query = "SELECT COUNT(*) FROM vijay WHERE username = @Username AND password = @Password";

        // Create a SqlCommand object with the query and connection
        using (SqlCommand command = new SqlCommand(query, connection))
        {
            // Set the parameter values for username and password
            command.Parameters.AddWithValue("@Username", enteredUsername);
            command.Parameters.AddWithValue("@Password", enteredPassword);

            // Execute the query and get the result
            int result = (int)command.ExecuteScalar();

            // Check the result to determine if the login is successful
            if (result > 0)
            {
                MessageBox.Show("Login successful");
            }
            else
            {
                MessageBox.Show("Invalid username or password");
            }
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show("An error occurred: " + ex.Message);
    }
}
}