Troubles with using twice exec_sql in a procedure

Question

Then I've written a procedure (1), using exec_sql.execute, that executes an SQL string, given the number of columns.
Then, I've written a procedure (2), using exec_sql.describe_column, that identifies the columns in the result of an SQL string.
Both of them work.
So I tried to merge them, so I shouldn't need to know how many columns I have to extract in the procedure (2), but, after executing the "(1)" part, an exception (ORA-306500: non-Oracle exception) is thrown when "res := exec_sql.execute(cursID)" is executed.
Excluding exclusively one of the two parts with /* and */, I see that each part, stand alone from another, works!
I use the same cursor (exec_sql.curstype) for both parts. I've also tried to use two different cursors, closing the former before opening the latter, but the results don't change.
Where is the trouble?
Thanks in advance.

Answer 1

Here is the code. Thanks in advance.
procedure push_xls_query(wh text_io.file_type, wh_web varchar2, titolo varchar2, testoquery varchar2) is
     type stringArray is table of varchar2(500) index by binary_integer;
     type intArray is table of pls_integer index by binary_integer;
     valori stringArray;
     tipi intArray;
     nRows number := 0;
     i number := 0;
     cursorID exec_sql.curstype;
     result pls_integer;
     colName varchar2(30);
     colLen number;
     colType pls_integer;
     numerocampi number;
     temp1 varchar2(80);
begin
     -- Se la lunghezza del titolo e' maggiore di 31 caratteri, lancia una eccezione
     if length(titolo) > 31 then
          raise xls_exception;
     end if;
     pkg_txt_io.putline(wh, wh_web, '<Worksheet ss:Name="'||to_xml(titolo)||'"><Table>');
     numerocampi := 0;
cursorID := exec_sql.open_cursor;
exec_sql.parse(cursorID, testoquery, exec_sql.V7);
message('Prima di execute'); message(' ', no_acknowledge);
     result := exec_sql.execute(cursorID);
message('Dopo di execute'); message(' ', no_acknowledge);
     -- Stampa i nomi dei campi
     pkg_txt_io.putline(wh, wh_web,'<Row>');
     loop
          numerocampi:=numerocampi+1;
          begin
               exec_sql.describe_column(cursorID, numerocampi, colName, colLen, colType);
               tipi(numerocampi) := colType;
               if colType in (exec_sql.NUMBER_TYPE,
                         exec_sql.FLOAT_TYPE,
                         exec_sql.ROWID_TYPE) then
                    temp1 := 'rightbold';
               else
                    temp1 := 'bold';
               end if;
               pkg_txt_io.putline(wh, wh_web, '<Cell ss:StyleID="'||temp1||'"><Data ss:Type="String">'||to_xml(colName)||'</Data></Cell>');
          exception
               when others then
                    if sqlcode=1 then -- -306500 then
                         exit;
                    else
                         message('Errore imprevisto: '||SQLCODE||' - '||SQLERRM);
                         message(' ', no_acknowledge);
                         return;
                    end if;
          end;
     end loop;
     pkg_txt_io.putline(wh, wh_web,'</Row><Row></Row>');
i := 1;
while i <= numerocampi loop
valori(i) := null;
exec_sql.define_column(cursorID, i, valori(i), 500);
i := i+1;
end loop;
while (exec_sql.fetch_rows(cursorID)>0) loop
nRows := nRows + 1;
     pkg_txt_io.putline(wh, wh_web, '<Row>');
i := 1;
while i <= numerocampi loop
exec_sql.column_value(cursorID, i, valori(i));
          if tipi(i) in (exec_sql.NUMBER_TYPE,
                         exec_sql.FLOAT_TYPE,
                         exec_sql.ROWID_TYPE) then
               temp1 := 'Number';
          else
               temp1 := 'String';
          end if;
          pkg_txt_io.putline(wh, wh_web, '<Cell><Data ss:Type="'||temp1||'">'||to_xml(valori(i))||'</Data></Cell>');
i := i+1;
end loop;
     pkg_txt_io.putline(wh, wh_web, '</Row>');
end loop;
     exec_sql.close_cursor(cursorID);
     pkg_txt_io.putline(wh, wh_web, '</Table></Worksheet>');
end;
procedure push_xls_simplequery(filename varchar2, testoquery varchar2) is
     wh text_io.file_type;
     wh_web varchar2(1);
begin
     begin
          pkg_txt_io.delete_temp_file(filename);
     exception
          when pkg_txt_io.ex_web_io then null;
     end;
     pkg_txt_io.open(filename, 'w', wh, wh_web);
     push_xls_begin(wh, wh_web);
     push_xls_query(wh, wh_web, 'Sheet1', testoquery);
     push_xls_end(wh, wh_web);
     pkg_txt_io.close(wh, wh_web);
end;