ดึงข้อมูลจากฐานข้อมูลแสดงบน label กรณี join table หลายๆ ตารางได้หรือป่าวครับ มีcode

 conn = new OdbcConnection(connectionString);
                conn.Open();
                string StrFind = comboBox1.Text;
                string StrFindMem = textBox2.Text;
  da = default(OdbcDataAdapter);
                dt = new DataTable();
                //string sql = "SELECT mem_id,br_no FROM loan_m_register where mem_id='" + StrFindMem + "'and br_no='" + StrFind + "'";
                string sql = "SELECT a.mem_id FROM loan_m_register a LEFT JOIN loan_m_contact b ON (a.lreg_recno = b.lreg_recno) and (a.code = b.code) and (a.br_no = b.br_no) where a.mem_id='" + StrFindMem + "'and a.br_no='" + StrFind + "'and b.lcont_id like'สม%'order by b.lcont_id";
                cmd = new OdbcCommand();
                da = new OdbcDataAdapter(sql, conn);
                da.Fill(dt);

                if (dt.Rows.Count > 0)
                {

                    this.label4.Text = dt.Rows[0]["a.mem_id"].ToString();
                }

                conn.Close();