public partial class Form1 : Form
{
   private  OleDbConnection connection = new OleDbConnection();
    public Form1()
    {
        InitializeComponent();
 connection.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=‪‪C:UsersBahoDesktopUAVUAVbinDebuguav.accdb;
  Persist Security Info=False;";
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        try
        {
        connection.Open();
        checkConnection.Text = "Connection Successful";
        connection.Close();
        }

        catch (Exception ex)
        {
            MessageBox.Show("Error  " + ex);
        }
    }

    private void btnLogin_Click(object sender, EventArgs e)
    {
        connection.Open();
        OleDbCommand command = new OleDbCommand();
        command.Connection = connection;
        command.CommandText = "select * from Login where UserName='"+ txtUserName.Text+ "' and Password='"+ txtPassword.Text + "'";

        OleDbDataReader reader = command.ExecuteReader();
        int count = 0;
        while (reader.Read())
        {
            count = count + 1;
        }
        if(count==1)
        {
            MessageBox.Show("Username and Password is correct");
            connection.Close();
            connection.Dispose();
            this.Hide();
            Form2 f2= new Form2();
            f2.ShowDialog();

        }
        else if (count > 1)
        {
            MessageBox.Show("Duplicate Username and Password");
        }
        else
        {
            MessageBox.Show("Username and Password is not correct");
        }
        connection.Close();
    }
}

public partial class Form1 : Form
 {
    private string connectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=‪‪C:UsersBahoDesktopUAVUAVbinDebuguav.accdb;Persist Security Info=False;";

    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        try
        {
            using (var connection = new OleDbConnection(connectionString))
            {
                connection.Open();
                checkConnection.Text = "Connection Successful";
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show("Error  " + ex);
        }
    }

    private void btnLogin_Click(object sender, EventArgs e)
    {
        var numberOfLogins = 0;
        using (var connection = new OleDbConnection(connectionString))
        {
            connection.Open();
            var commandText = "select * from Login where UserName=@UserName and Password=@Password";
            using (var command = new OleDbCommand(commandText, connection))
            {
                command.Parameters.AddWithValue("UserName", txtUserName.Text);
                command.Parameters.AddWithValue("Password", txtPassword.Text);

                using (var reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        numberOfLogins = numberOfLogins + 1;
                    }
                }
            }
        }

        if (count == 1)
        {
            MessageBox.Show("Username and Password is correct");
            this.Hide();

            Form2 f2 = new Form2();
            f2.ShowDialog();
        }
        else if (count > 1)
        {
            MessageBox.Show("Duplicate Username and Password");
        }
        else
        {
            MessageBox.Show("Username and Password is not correct");
        }
    }
}