READ v17

The READ procedure reads a portion of a large object into a buffer starting at the specified offset.

READ(<lob_loc> { BLOB | CLOB }, <amount> IN OUT NUMBER,
  <offset> NUMBER, <buffer> OUT { RAW | VARCHAR2 })

READ(<file_loc> { BFILE }, <amount> IN OUT NUMBER,
  <offset> IN NUMBER, <buffer> OUT { RAW })

Parameters

lob_loc

Large object locator of the large object to read.

file_loc

File locator of the BFILE to read.

amount

Number of bytes/characters read. If there's no more data to read, then amount returns 0 and a DATA_NOT_FOUND exception is thrown.

offset

Position to begin reading. The first byte/character is position 1.

buffer

Variable to receive the large object. If lob_loc is a BLOB, then buffer must be RAW. If lob_loc is a CLOB, then buffer must be VARCHAR2. If file_loc is BFILE, then buffer must be RAW.

Example

DECLARE
   src_loc  bfile := BFILENAME('ANOTHER_DIR', 'a.txt');
   Buffer   RAW(1024);
   Amount   NUMBER := 1024;
   Position NUMBER := 1;
BEGIN
  /* Opening the source BFILE is mandatory */
  DBMS_LOB.OPEN (src_loc, DBMS_LOB.LOB_READONLY);
  DBMS_LOB.READ (src_loc, Amount, Position, Buffer); 
 /* Close the BFILE: */
  DBMS_LOB.FILECLOSE(src_loc);
  COMMIT;
END;