How to Write Blob from Oracle Column to the File System - sql

Question

my_images table consists of a blob column called images. I need to write these images to my image_dir which is 'C:\TEMP'.
When the following PL/SQL code is executed, only the first image is written to the directory as an image. The second blob is written as 0 byte (empty) and there is no other (Should be a total number of 8).
So the loop does not seem to work correctly. I am using Oracle 11g Express Edition (XE) and SQL Developer. Here is the error and the code:
Error starting at line : 53 in command -
BEGIN write_blob_to_file_v5; END;
Error report -
ORA-01403: no data found
ORA-06512: at "SYS.DBMS_LOB", line 1056
ORA-06512: at "SYS.WRITE_BLOB_TO_FILE_V5", line 40
ORA-06512: at line 1
01403. 00000 - "no data found"
*Cause: No data was found from the objects.
*Action: There was no data from the objects which may be due to end of fetch.
PL/SQL code
CREATE OR REPLACE PROCEDURE write_blob_to_file_v5
AS
v_lob_image_name VARCHAR (100);
v_lob_image_id NUMBER;
v_blob BLOB;
v_buffer RAW (32767);
v_buffer_size BINARY_INTEGER;
v_amount BINARY_INTEGER;
v_offset NUMBER (38) := 1;
v_chunksize INTEGER;
v_out_file UTL_FILE.file_type;
BEGIN
FOR i IN (SELECT DBMS_LOB.getlength (v_blob) v_len,
image_id v_lob_image_id,
"IMAGE_NAME" v_lob_image_name,
image v_blob
FROM sys.MY_IMAGES)
LOOP
v_chunksize := DBMS_LOB.getchunksize (i.v_blob);
IF (v_chunksize < 32767)
THEN
v_buffer_size := v_chunksize;
ELSE
v_buffer_size := 32767;
END IF;
v_amount := v_buffer_size;
DBMS_LOB.open (i.v_blob, DBMS_LOB.lob_readonly);
v_out_file :=
UTL_FILE.fopen (
location => 'IMAGE_DIR',
filename => ( ''
|| i.v_lob_image_id
|| '_'
|| i.v_lob_image_name
|| '.JPG'),
open_mode => 'wb',
max_linesize => 32767);
WHILE v_amount >= v_buffer_size
LOOP
DBMS_LOB.read (i.v_blob,
v_amount,
v_offset,
v_buffer);
v_offset := v_offset + v_amount;
UTL_FILE.put_raw (file => v_out_file,
buffer => v_buffer,
autoflush => TRUE);
UTL_FILE.fflush (file => v_out_file);
--utl_file.new_line(file => v_out_file);
END LOOP;
UTL_FILE.fflush (v_out_file);
UTL_FILE.fclose (v_out_file);
DBMS_LOB.close (i.v_blob);
END LOOP;
END;

Answer 1

The main problem is related NOT to re-initialize the parameter v_offset to 1 ( as in the declaration section ) :
v_offset := 1;
for every image id just before
v_chunksize := dbms_lob.getchunksize(i.v_blob);
assignment.
Moreover, the problem may arise about not yet closed or already opened blobs. To prevent these,
replace
dbms_lob.open(i.v_blob,dbms_lob.lob_readonly);
with
if ( dbms_lob.isopen(i.v_blob)=0 ) then
dbms_lob.open(i.v_blob,dbms_lob.lob_readonly);
end if;
and
replace
dbms_lob.close(i.v_blob);
with
if ( dbms_lob.isopen(i.v_blob)=1 ) then
dbms_lob.close(i.v_blob);
end if;