Converting BLOB to Varchar

Question

How can I convert a large BLOB to a varchar within Oracle? I tried to fetch the BLOB field to put into a VARCHAR2 field, but, if I select more than 4000, It is throwing an error - ORA:06502 PL/SQL: numeric or value error: raw variable length too long.
Here is the query I executed for the blob datatype conversion in crystal reports and works fine but I am losing half of the document. If I put 4001, I get the error message above.
SELECT package_id,
(dbms_lob.substr(STORED_DOCS(IMPORT_PACKAGE_STORE. STORED_DOCUMENT),4000)) as stored
FROM
IMPORT_PACKAGE_STORE
where package_id=1
Here's the function STORED_DOCS...
create or replace function STORED_DOCS(B BLOB)
return clob is
c clob;
n number;
begin
if (b is null) then
return null;
end if;
if (length(b)=0) then
return empty_clob();
end if;
dbms_lob.createtemporary(c,true);
n:=1;
while (n+32767<=length(b)) loop
dbms_lob.writeappend(c,32767,utl_raw.cast_to_varchar2(dbms_lob.substr(b,32767,n)));
n:=n+32767;
end loop;
dbms_lob.writeappend(c,length(b)-n+1,utl_raw.cast_to_varchar2(dbms_lob.substr(b,length(b)-n+1,n)));
return c;
end;
My question is: Is there any way to fetch more than 4000 char BLOB field into a VARCHAR2 field.?

Answer 1

dhanu !! wrote:
Hi,
I have a table with a column type blob. This column has a file contents which is either encoded in utf-8 or utf-16 format. When the encoding is utf-16, if query the database and try access the column contents by converting blob data into clob (or blob to varchar)How do you check this? Is there any other column in the table which stores this information?
- I do not see any valid data in the query result. All I get is inverted "?" and boxes suggesting invalid data.Most probably database and client character set mismatch or your client is not able to render the required font?