ถามหน่อยคับ อยากทราบ วิธีเช็คว่า ถ้าข้อมูลที่ค้นหาไม่มี ให้show อีก form หนึ่งขึ้นมาต้องเขียนcode ยังไงคับ

sb.Remove(0, sb.Length);
                sb.Append("select*from in_goods where fg_code ='" + textBox1.Text + "'");
                string sqlingoods = sb.ToString();
                da = new SqlDataAdapter(sqlingoods, con);
                DataTable dt = new DataTable();
                da.Fill(dt);
                
                this.dataGridView1.DataSource = dt;
                this.dataGridView1.Columns.Clear();
                var wiht1 = dataGridView1.ColumnHeadersDefaultCellStyle;
                wiht1.BackColor = Color.Navy;
                wiht1.ForeColor = Color.White;
                wiht1.Font = new Font(dataGridView1.Font, FontStyle.Bold);
                DataGridViewTextBoxColumn colomn1 = new DataGridViewTextBoxColumn();

                colomn1 = new DataGridViewTextBoxColumn();
                colomn1.DataPropertyName = "ou_code";
                colomn1.HeaderText = "บริษัท";
                colomn1.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter;
                colomn1.Width = 100;
                this.dataGridView1.Columns.Add(colomn1);

                colomn1 = new DataGridViewTextBoxColumn();
                colomn1.DataPropertyName = "fg_code";
                colomn1.HeaderText = "รหัสสินค้า";
                colomn1.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter;
                colomn1.Width = 100;
                this.dataGridView1.Columns.Add(colomn1);

                colomn1 = new DataGridViewTextBoxColumn();
                colomn1.DataPropertyName = "fg_name";
                colomn1.HeaderText = "รายละเอียด";
                colomn1.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter;
                colomn1.Width = 100;
                this.dataGridView1.Columns.Add(colomn1);

                colomn1 = new DataGridViewTextBoxColumn();
                colomn1.DataPropertyName = "old_price";
                colomn1.HeaderText = "ราคาป้าย";
                colomn1.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter;
                colomn1.Width = 100;
                this.dataGridView1.Columns.Add(colomn1);

                colomn1 = new DataGridViewTextBoxColumn();
                colomn1.DataPropertyName = "u_price";
                colomn1.HeaderText = "ราคาขาย";
                colomn1.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter;
                colomn1.Width = 100;
                this.dataGridView1.Columns.Add(colomn1);

                colomn1 = new DataGridViewTextBoxColumn();
                colomn1.DataPropertyName = "cost";
                colomn1.HeaderText = "ราคาต้นทุน";
                colomn1.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter;
                colomn1.Width = 100;
                this.dataGridView1.Columns.Add(colomn1);