title: Using CLOB gives ORA-06502: PL/SQL: numeric or value error
body: <p>Code below throws me an error: "ORA-06502: PL/SQL: numeric or value error
  ORA-06512: at line 24".</p>
  
  <pre><code>DECLARE 
  v_clob CLOB;
  CURSOR cur_a
  IS
  SELECT
  device_num,
  Account_number,
  CustomerName,
  Prem_address ,
        contact_phone ,
        W_status ,
        A_status ,
        "12-1 AM" Twelve21,
        "1-2 AM" One22,
        "2-3 AM" Two23,
        "3-4 AM" Three24,
        CIn4Hrs
      FROM account a
      WHERE 1 =1 ;
  BEGIN
    DBMS_LOB.CreateTemporary( v_clob, true );
    FOR rec IN cur_a
    LOOP
      v_clob := v_clob ||rec.device_num|| ',' ||rec.Account_number|| ',' ||rec.contact_phone || ',' ||rec.W_status|| ',' ||rec.A_status|| ',' ||rec.Twelve21|| ',' ||rec.One22|| ',' ||rec.Two23|| ',' ||rec.Three24|| ',' ||rec.CIn4Hrs|| ',' ||SUBSTR(rec.CustomerName,1,15)|| ',' ||SUBSTR(rec.Prem_address,1,15) || UTL_TCP.crlf;
    END LOOP;
  END; 
  </code></pre>