Update the table with the above query

ITS URGENT

I want to update the xxacl_pn_new_cha_part table with the query below.
Here is my code:-
protected void btnUpdate_Click(object sender, EventArgs e) { OracleConnection conn = new OracleConnection(ConfigurationManager.ConnectionStrings["OracleConn"].ConnectionString); string strQuery = "SELECT ab.broker_id,CASE WHEN SYSDATE - la.creation_date <= 180 THEN 'A' WHEN SYSDATE - cef_dt <= 30 THEN 'B' ELSE 'C'END rating " + "FROM xxacl_pn_new_cha_part ab,xxacl_pn_lease_det ld,xxacl_pn_leases_all la,xxcus.xxacl_pn_customer_enquiry_v ce " + "WHERE ab.broker_id = ld.broker_id AND ld.booking_no = la.booking_no AND ab.broker_id = ce.broker_id"; // this is my query OracleCommand cmd = new OracleCommand(); cmd.CommandType = CommandType.Text; cmd.Comm ...