System.InvalidOperationException: "Fill: Свойство SelectCommand.Connection не инициализировано."

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
 
namespace WorkingBD
{
    public partial class LoginForm : Form
    {
        public LoginForm()
        {
            InitializeComponent();
            this.passField.AutoSize = false;
            this.passField.Size = new Size(this.passField.Size.Width, 64);
        }
 
        private void CloseButton_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }
 
        private void CloseButton_MouseEnter(object sender, EventArgs e)
        {
            CloseButton.ForeColor = Color.Green;
        }
 
        private void CloseButton_MouseLeave(object sender, EventArgs e)
        {
            CloseButton.ForeColor = Color.Red;
        }
 
        Point lastPoint;
 
        private void mainPanel_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                this.Left += e.X - lastPoint.X;
                this.Top += e.Y - lastPoint.Y;
            }
        }
 
        private void mainPanel_MouseDown(object sender, MouseEventArgs e)
        {
            lastPoint = new Point(e.X, e.Y);
        }
 
        private void Login_label_Click(object sender, EventArgs e)
        {
            this.Hide();
           /* RegisterForm registerform = new RegisterForm();
            registerform.Show(); */
        }
 
        private void Login_label_MouseEnter(object sender, EventArgs e)
        {
            Login_label.ForeColor = Color.Green;
        }
 
        private void Login_label_MouseLeave(object sender, EventArgs e)
        {
            Login_label.ForeColor = Color.Black;
        }
 
        private void ButtonLogin_Click(object sender, EventArgs e)
        {
            string loginUser = loginField.Text;
            string passUser = passField.Text;
 
            DB db = new DB();
 
            DataTable table = new DataTable();
 
            SqlDataAdapter adapter = new SqlDataAdapter();
 
            SqlCommand command = new SqlCommand("SELECT * FROM `User` WHERE `login` = @UG AND `pass` = @UP", db.getConnection());
            command.Parameters.Add("@UG", SqlDbType.NVarChar).Value = loginUser;
            command.Parameters.Add("@UP", SqlDbType.NVarChar).Value = passUser;
 
            adapter.SelectCommand = command;
            adapter.Fill(table);
 
            if (table.Rows.Count > 0)
                MessageBox.Show("Yes");
            else
                MessageBox.Show("No");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace WorkingBD
{
    class DB
    {
        public SqlConnection sqlConnection;
 
        public void createConnection()
        {
            string connectionString = @"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\Администратор\source\repos\WorkingBD\WorkingBD\Database2.mdf;Integrated Security=True";
 
            sqlConnection = new SqlConnection(connectionString);
 
            sqlConnection.Open();
        }
 
        public void openConnection()
        {
            if (sqlConnection.State == ConnectionState.Closed)
                sqlConnection.Open();
        }
        
        public void closeConnection()
        {
            if (sqlConnection.State == ConnectionState.Open)
                sqlConnection.Close();
        }
 
        public SqlConnection getConnection()
        {
           return sqlConnection;
        }
    }
}