Using CLOB as a VARCHAR2 to write a string

Question

Hello everyone:
I have this situation:
After a query, i need to order the query rows in a table. To do this, i write a string using HTML format. Then, i send the string (message) by email, and i save the same in a table (database).
The message, must be 32767 as a maximun number of characters. Because, the message is a VARCHAR2.
When the number of characters is greater than 32767, in can't use this way.
So, i trying to use a CLOB datatype, but i don't know how to write the string and then, send it by email.
I wrote this code:
xSGLOSA_UNO$ CLOB;
xSGLOSA_UNO$ := '<table border="1"><tr>FECHA DE PROCESOS CORRECTAS</tr>';
xSGLOSA_UNO$ := xSGLOSA_UNO$ || '<tr><td>Rut Operador</td><td>Nombre</td><td>Proceso</td><td>Fecha Proceso</td></tr>';
BEGIN
FOR CONSULTA_UNO IN(
SELECT
FPR_NRUTOPERADOR,
OPE_SNOMBRE,
FPR_SCODPROCESO,
FPR_DFHOPROCESO
FROM
FECHAS_PROCESO,
OPERADOR
WHERE
TRUNC(FPR_DFHOPROCESO) = TRUNC(SYSDATE)
LOOP
xSGLOSA_UNO$ := xSGLOSA_UNO$ ||  '<tr><td>' || CONSULTA_UNO.FPR_NRUTOPERADOR || '</td><td>' || CONSULTA_UNO.OPE_SNOMBRE || '</td><td>' || CONSULTA_UNO.FPR_SCODPROCESO || '</td><td>' || CONSULTA_UNO.FPR_DFHOPROCESO || '</td></tr>';
END LOOP;
xSGLOSA_UNO$ := xSGLOSA_UNO$ || '</table>';
EXCEPTION
WHEN OTHERS THEN
NUMERROR$ := SQLCODE;
MSJERROR$ := '[NES$FECHA_PROCESOS] FECHAS CORRECTAS (' || SQLERRM || ')';
RETURN;
END;
And i have this error:
[NUMERROR$:=-6502], [MSJERROR$:=[NES$FECHA_PROCESOS] FECHAS CORRECTAS (ORA-06502: PL/SQL: error  numérico o de valor)]
Please, help me with this issue. I am new in Oracle, and i don't have idea the real reason for this.
Thank you for support.

Answer 1

Now... when you do things like:
xSGLOSA_UNO$ := xSGLOSA_UNO$ || '</table>';
then you are concatenating a CLOB (xSGLOSA_UNO$) to a VARCHAR2 ('</table>') which can be done by either convert the clob to varchar2 or the varchar2 to clob before concatenating. || is a overloaded function which accepts two varchar2 or two clob parameters (amongst others). As the CLOB gets bigger than 32k you cannot just let oracle decide how to convert so, you should do:
xSGLOSA_UNO$ := xSGLOSA_UNO$ || TO_CLOB('</table>');
instead.
And this at every place where you concatenate
eg here too:
xSGLOSA_UNO$ := xSGLOSA_UNO$ || TO_CLOB('<tr><td>') || CONSULTA_UNO.FPR_NRUTOPERADOR || TO_CLOB('</td><td>') || CONSULTA_UNO.OPE_SNOMBRE || TO_CLOB('</td><td>') || CONSULTA_UNO.FPR_SCODPROCESO || TO_CLOB('</td><td>') || CONSULTA_UNO.FPR_DFHOPROCESO || TO_CLOB('</td></tr>');
I don't know the datatypes of CONSULTA_UNO.FPR_NRUTOPERADOR and the other components used...if they are VARCHAR then convert, if they are CLOB then let them like they are.
hth