how to unload a BLOB to a OS file

How to Load File Content to a BLOB Field and Unload BLOB Content to a File on the OS [ID 471715.1]

Applies to:

Oracle Server - Enterprise Edition - Version: 10.2.0.1 to 10.2.0.3
Information in this document applies to any platform.

Goal

This note describes steps to Load a Binary file into a BLOB Column of a table, and also describes how to unload contents of a blob column to a file on the filesystem.

Solution

Load contents of Binary File to a blob column of a table
Create these 2 tables
SQL> CREATE TABLE MYLOB ( ID NUMBER, PHOTO BLOB ) ;
SQL> CREATE TABLE TEMP_BFILE( B_FILE BFILE) ;
Insert bfile locator for the binary file into temp_file SQL> insert into temp_bfile values ( bfilename('MYDIR','pic1.jpg'));
MYDIR is a directory object created with the CREATE DIRECTORY command.
Inserting lob into file
SQL> declare
tmp_blob blob default EMPTY_BLOB();
tmp_bfile bfile:=null;
dest_offset integer:=1;
src_offset integer:=1;
begin
select b_file into tmp_bfile from temp_bfile;
DBMS_LOB.OPEN (tmp_bfile, DBMS_LOB.FILE_READONLY);
dbms_lob.createtemporary(tmp_blob, TRUE);
DBMS_LOB.LOADBLOBFROMFILE(tmp_blob,tmp_bfile,DBMS_LOB.LOBMAXSIZE,dest_offset,src_offset);
insert into mylob values(1,tmp_blob);
DBMS_LOB.CLOSE(tmp_bfile);
commit;
end;
Unload contents of a blob column of a table to a file on the filesystem
Offload the blob to a file SQL> declare
tmp_blob blob default empty_blob();
begin
dbms_lob.createtemporary(tmp_blob, true);
select photo into tmp_blob from mylob;
sys.retrieve_lob_to_file (tmp_blob, 'MYDIR','mypic1.jpg');
end;
/
Note : MYDIR is a directory object created with the CREATE DIRECTORY command

Source for procedure retrieve_lob_to_file
CREATE OR REPLACE PROCEDURE retrieve_lob_to_file(temp_blob in BLOB, file_path in varchar2, file_name in varchar2) IS
data_buffer RAW (32767);
position INTEGER := 1;
filehandle utl_file.file_type;
error_number NUMBER;
error_message VARCHAR2(100);
blob_length INTEGER;
chunk_size BINARY_INTEGER := 32767;
BEGIN
blob_length := dbms_lob.getlength(temp_blob);

filehandle := utl_file.fopen(file_path, file_name,'wb', 1024);

WHILE position < blob_length LOOP

dbms_lob.read (temp_blob, chunk_size, position, data_buffer);

utl_file.put_raw (filehandle, data_buffer);

position := position + chunk_size;

data_buffer := null;

END LOOP;

utl_file.fclose(filehandle);


EXCEPTION
WHEN OTHERS THEN
BEGIN
error_number := sqlcode;
error_message := substr(sqlerrm ,1 ,100);
dbms_output.put_line('Error #: ' || error_number);
dbms_output.put_line('Error Message: ' || error_message);
utl_file.fclose_all;
END;
END;
/