How to read the blob column?

Question

Hi,
i wanted to store the zip file in a blob column and i also want to download the file
i have tried in the following manner
-- Creation of the table
create table demo
( ID int,
theblob blob);
--insert the zip file into the table
declare
l_blob blob;
l_bfile bfile;
begin
insert into demo values ( 5, empty_blob() )
returning theBlob into l_blob;
l_bfile := bfilename( 'MWDIR_TST', 'demo.zip' );
dbms_lob.fileopen( l_bfile );
dbms_lob.loadfromfile( l_blob, l_bfile,
dbms_lob.getlength( l_bfile ) );
dbms_lob.fileclose( l_bfile );
end;
-- Function to convert the blob into clob
CREATE OR REPLACE FUNCTION XBLOB_To_CLOB(L_BLOB BLOB) RETURN CLOB IS
L_CLOB               CLOB;
L_SRC_OFFSET     NUMBER;
L_DEST_OFFSET     NUMBER;
L_BLOB_CSID          NUMBER := DBMS_LOB.DEFAULT_CSID;
V_LANG_CONTEXT     NUMBER := DBMS_LOB.DEFAULT_LANG_CTX;
L_WARNING          NUMBER;
L_AMOUNT          NUMBER;
BEGIN
IF DBMS_LOB.GETLENGTH(L_BLOB) > 0 THEN
DBMS_LOB.CREATETEMPORARY(L_CLOB, TRUE);
L_SRC_OFFSET := 1;
L_DEST_OFFSET := 1;
L_AMOUNT := DBMS_LOB.GETLENGTH(L_BLOB);
DBMS_LOB.CONVERTTOCLOB(L_CLOB,
L_BLOB,
L_AMOUNT,
L_SRC_OFFSET,
L_DEST_OFFSET,
1,
V_LANG_CONTEXT,
L_WARNING);
RETURN L_CLOB;
ELSE
L_CLOB:= TO_CLOB('');
RETURN L_CLOB;
End IF;
DBMS_LOB.FREETEMPORARY(L_CLOB);
END XBLOB_To_CLOB;
-- Procedure to wtire clob into file
CREATE OR REPLACE PROCEDURE Write_CLOB_To_File ( directory_name varchar2,filename varchar2, clob_loc CLOB )
IS
buffer VARCHAR2(32767);
buffer_size CONSTANT BINARY_INTEGER := 32767;
amount BINARY_INTEGER;
offset NUMBER(38);
file_handle UTL_FILE.FILE_TYPE;
BEGIN
file_handle := UTL_FILE.FOPEN(location => directory_name,filename => filename,open_mode => 'w',max_linesize => buffer_size);
amount := buffer_size;
offset := 1;
-- READ FROM CLOB / WRITE OUT TO DISK
WHILE amount >= buffer_size
LOOP
DBMS_LOB.READ(lob_loc => clob_loc,amount => amount,offset => offset,buffer => buffer);
buffer:=replace(buffer,chr(13),'');
offset := offset + amount;
UTL_FILE.PUT(file => file_handle,buffer => buffer);
UTL_FILE.FFLUSH(file => file_handle);
END LOOP;
UTL_FILE.FCLOSE(file => file_handle);
END Write_CLOB_To_File;
-- To execute use the following example
declare TmpClob CLOB;
begin
select XBLOB_TO_CLOB(theblob) into TmpClob from demo where id=5;
Write_Clob_To_File('TEMP','demo.txt',TmpClob);
end;
when i am excuting the above code it is not bringing the exact binary values from the database ?
can any one help me on this?
Thanks
Rangan S

Answer 1

On another note it's always a good idea to tell us what database version you are using e.g. 9.2.0.7 or 10.2.0.3 etc. as this will allow us to tailor our answers appropriately in case there are features we can't use because you are using an older version.
And, when posting code, please put {noformat}{noformat} tags around it so that it keeps its formatting on the forum.