Pl/SQL block for BLOB

Question

Hi,
I wrote a function to convert from blob to varcahr2 as like bellow.how can i test this function(give me any anonomous block for test.)
create or replace FUNCTION BLOBCONVERT
( var_gdtxft blob)
return varchar2 is
var_text VARCHAR2(6000);
BEGIN
SELECT REPLACE(REPLACE(substr(UTL_RAW.CAST_TO_varchar2(var_GDTXFT),321, LENGTH(UTL_RAW.CAST_TO_varchar2(var_GDTXFT))-5-321),
SUBSTR(substr(UTL_RAW.CAST_TO_varchar2(var_GDTXFT),321),2,1),''),'\par','\n') into var_text
FROM dual;
RETURN var_text;
EXCEPTION
When NO_DATA_FOUND then
RETURN 'No Data found';
END BLOBCONVERT;

Answer 1

I don't quite get what your function is supposed to do, but in any case in can simplified a bit (probably still more if you explained us what you'd like to achieve):
SQL> create or replace function blobconvert (var_gdtxft blob)
   return varchar2
is
begin
   return replace
            (replace (substr (utl_raw.cast_to_varchar2 (var_gdtxft),
                              321,
                                length (utl_raw.cast_to_varchar2 (var_gdtxft))
                              - 5
                              - 321
                      substr (substr (utl_raw.cast_to_varchar2 (var_gdtxft),
                                      321
                              2,
                              1
             '\par',
             '\n'
end blobconvert;
Function created.
SQL> declare
   bl   blob := utl_raw.cast_to_raw ('Hello \n World \par' || rpad ('World', 400, 'World'));
begin
   dbms_output.put_line (blobconvert (bl));
end;
oldWoldWoldWoldWoldWoldWoldWoldWoldWoldWoldWoldWoldWoldWoldWoldWoldWoldWol
PL/SQL procedure successfully completed.