(a) Initialize it by Empty_Blob() function.
(b) Create a directory in Oracle corresponding to OS Dir
from which you wish to load BLOB data.
(c) Use DBMS_LOB package to load data. It has various
functions like DBMS_LOB.LOADFROMFILE.
(d) For an example, see http://www.dbasupport.com/forums/showthread.php?
2. No. It is not Null. The Column is Empty and is used for
initialization so that it contains a locator.
3. SQL PLUS cannot display lob columns, and thus you
cannot 'select' BLOB column as you would other
datatypes. However, you can develop your own
procedures using DBMS_LOB package or other
languages like PHP, Java etc.