C#

private void button14_Click(object sender, EventArgs e)
       {
           if (textBox9.Text != "" && textBox10.Text != "")
           {
               string connectionString;
               MySqlConnection cnn;
               connectionString = @"Data Source=localhost;Initial Catalog=testDB;User ID=root;Password=mysql";
               cnn = new MySqlConnection(connectionString);
               string id = textBox9.Text;
               string password = textBox10.Text;
               textBox9.Text = "";
               textBox10.Text = "";
               string query = "select count(*) from login where userid=@userid and password=@password";
               using (MySqlCommand cmd = new MySqlCommand(query))
               {
                   cmd.Parameters.AddWithValue("@userid", id);
                   cmd.Parameters.AddWithValue("@password", password);
                   cmd.Connection = cnn;
                   cnn.Open();
                   cmd.ExecuteNonQuery();
                   int result = Convert.ToInt32(cmd.ExecuteScalar());
                   DialogResult dr = MessageBox.Show("Are you sure to Login now?", "Confirmation", MessageBoxButtons.YesNo);
                   if (dr == DialogResult.Yes && result > 0)
                   {
                       MessageBox.Show("Login Successfully");
                       cnn.Close();
                       this.Hide();
                       Form2 f2 = new Form2();
                       f2.ShowDialog();
                   }
                   else
                   {
                       MessageBox.Show("Login Failed");
                   }
               }
           }
           else
           {
               MessageBox.Show("Please Enter Correct Login details");
           }

       }
   }

string query = "select * from login where userid=@userid and password=@password";
                 using (MySqlCommand cmd = new MySqlCommand(query))
                {
                   cmd.Parameters.AddWithValue("@userid", id);
                   cmd.Parameters.AddWithValue("@password", password);
                    cmd.Connection = cnn;
                    cnn.Open();
                    cmd.ExecuteNonQuery();
                    DialogResult dr = MessageBox.Show("Are you sure to Login now?", "Confirmation Message", MessageBoxButtons.YesNo);
                    if (dr == DialogResult.Yes)
                    {
                        MessageBox.Show("Login Successfully");
                        cnn.Close();
                        this.Hide();
                        Form2 f2 = new Form2();
                        f2.ShowDialog();