How to include to tables in sql command display data from two tables in one datatable

private void Visaallakunder()
        {
            var dt = new DataTable();

            const string constring = @"Data Source = MARTIN; Initial Catalog = FakturaDB;Integrated Security = True";
            using (var con = new SqlConnection(constring))
            {
                using (var cmd = new SqlCommand("SELECT * FROM [FakturaDB].[dbo].[FakturaDB_Faktura] && FROM [FakturaDB].[dbo].[FakturaDB_Produkt]", con)
                    )
                {
                    dataGridViewAllaFakturor.ColumnCount = 5;
                    cmd.CommandType = CommandType.Text;
                    using (var sda = new SqlDataAdapter(cmd))
                    {
                        sda.Fill(dt);
                        dataGridViewAllaFakturor.AutoGenerateColumns = false;
                        dataGridViewAllaFakturor.ReadOnly = true;
                        dataGridViewAllaFakturor.Columns[0].DataPropertyName = "FakuturaNr";
                        dataGridViewAllaFakturor.Columns[0].Name = "FakturaNr";
                        dataGridViewAllaFakturor.Columns[0].HeaderText = @"FakturaNr";

                        dataGridViewAllaFakturor.Columns[1].DataPropertyName = "KundFaktura";
                        dataGridViewAllaFakturor.Columns[1].Name = "Kund";
                        dataGridViewAllaFakturor.Columns[1].HeaderText = @"Kund";

                        dataGridViewAllaFakturor.Columns[2].DataPropertyName = "FakturaDatumFran";
                        dataGridViewAllaFakturor.Columns[2].Name = "Skickad";
                        dataGridViewAllaFakturor.Columns[2].HeaderText = @"Skickad";

                        dataGridViewAllaFakturor.Columns[3].DataPropertyName = "Forfallodatum";
                        dataGridViewAllaFakturor.Columns[3].Name = "Förfaller";
                        dataGridViewAllaFakturor.Columns[3].HeaderText = @"Förfaller";


                        dataGridViewAllaFakturor.Columns[4].DataPropertyName = "PrisExklMoms";
                        dataGridViewAllaFakturor.Columns[4].Name = "Summa";
                        dataGridViewAllaFakturor.Columns[4].HeaderText = @"Summa";

                        
                    }
                    
                }
                dataGridViewAllaFakturor.DataSource = dt;
                

            }
        }

var dt = new DataSet();
            const string constring = @"Data Source = MARTIN; Initial Catalog = FakturaDB;Integrated Security = True";
            using (var con = new SqlConnection(constring))
            {
                con.Open();
                using (var cmd = new SqlCommand("SELECT * FROM [FakturaDB].[dbo].[FakturaDB_Faktura]; SELECT * FROM [FakturaDB].[dbo].[FakturaDB_Produkt];", con))
               
                    {
                        dataGridViewAllaFakturor.ColumnCount = 5;
                        cmd.CommandType = CommandType.Text;
                        using (var sda = new SqlDataAdapter(cmd))
                        {
                            sda.Fill(dt);
                            dataGridViewAllaFakturor.AutoGenerateColumns = false;
                            dataGridViewAllaFakturor.ReadOnly = true;
                            dataGridViewAllaFakturor.Columns[0].DataPropertyName = "FakuturaNr";
                            dataGridViewAllaFakturor.Columns[0].Name = "FakturaNr";
                            dataGridViewAllaFakturor.Columns[0].HeaderText = @"FakturaNr";
                            dataGridViewAllaFakturor.Columns[1].DataPropertyName = "KundFaktura";
                            dataGridViewAllaFakturor.Columns[1].Name = "Kund";
                            dataGridViewAllaFakturor.Columns[1].HeaderText = @"Kund";
                            dataGridViewAllaFakturor.Columns[2].DataPropertyName = "FakturaDatumFran";
                            dataGridViewAllaFakturor.Columns[2].Name = "Skickad";
                            dataGridViewAllaFakturor.Columns[2].HeaderText = @"Skickad";
                            dataGridViewAllaFakturor.Columns[3].DataPropertyName = "Forfallodatum";
                            dataGridViewAllaFakturor.Columns[3].Name = "Förfaller";
                            dataGridViewAllaFakturor.Columns[3].HeaderText = @"Förfaller";
                            dataGridViewAllaFakturor.Columns[4].DataPropertyName = "PrisExklMoms";
                            dataGridViewAllaFakturor.Columns[4].Name = "Summa";
                            dataGridViewAllaFakturor.Columns[4].HeaderText = @"Summa";
                    }
                }
                dataGridViewAllaFakturor.DataSource = dt;
                
            }