How can I extract files from an Oracle BLOB field?

问题:

I have a database which has a number of files stored in a BLOB field.

How can I extract & save the original files? There are many different file types - doc, pdf, xls, etc. The table has the extension in one col, and the original file name in another. There may be multiple files with the same file name, too.

回答1:

You can use the UTL_FILE package to do this in version 9i onwards

something like this:

DECLARE
  l_file      UTL_FILE.FILE_TYPE;
  l_buffer    RAW(32767);
  l_amount    BINARY_INTEGER := 32767;
  l_pos       NUMBER := 1;
  l_blob      BLOB;
  l_blob_len  NUMBER;
BEGIN

  SELECT blobcol
  INTO   l_blob
  FROM   table
  WHERE  rownum = 1;

  l_blob_len := DBMS_LOB.getlength(l_blob);

  -- Open the destination file.
  l_file := UTL_FILE.fopen(<location>,<filename>,'wb', 32767);

  WHILE l_pos < l_blob_len LOOP
    DBMS_LOB.read(l_blob, l_amount, l_pos, l_buffer);
    UTL_FILE.put_raw(l_file, l_buffer, TRUE);
    l_pos := l_pos + l_amount;
  END LOOP;

  -- Close the file.
  UTL_FILE.fclose(l_file);

END;
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