How can I add data to datatable and bind it to datagridview C#

I want to add many items after scan them one by one from database into datatable

public void CheckItem( string itemcode)
        {
            string constring = @"Data Source=.;Initial Catalog=pos;User id = sa;password=123";
            SqlCommand objCmd = new SqlCommand();
            objCmd.Parameters.Clear();
            using (SqlConnection objCnn = new SqlConnection(constring))
            {
                objCnn.Open();
                using (objCmd = objCnn.CreateCommand())
                {
                    objCmd.CommandType = CommandType.Text;
                    objCmd.CommandText = "SELECT  * FROM Items where Item_Code=@Item_Code";
                    objCmd.Parameters.Add(new SqlParameter("@Item_Code", itemcode));
                  
                    SqlDataReader myreader = objCmd.ExecuteReader();
                    DataTable dt = new DataTable();
                    dt.Load(myreader);
                     decimal sumprice=0;
                    if (dt.Rows.Count <= 0)
                     
// here i want to add new item into datatable , after that bind the new item with items that i added before 
 
 
                    dt = objDT.NewRow();
                    dt.Columns.Add("", typeof(decimal));
                  
                    dataGridView1.DataSource = dt;
 
                   
 
 
                }
            }
        }