What is the need of CLOB while having varchar,Bfile,NCLOB?

Clob are used to store the dat开发者_开发百科a character upto 4 GB. It is similar to Varchar. Then what is need for clob? We can use BFile to store documents,pdf.. and so on.

Then why we need CLOB?

CLOB: max. 8 TB(!) depending on DB block size - "DB character set"
NCLOB: max. 8 TB(!) depending on DB block size - "national character set"

VARCHAR: max. 2000 CHARs or 4000 BYTEs

BFILE: stores BINARY data in OS files instead of the DB itself (max. 4 GB)

http://download.oracle.com/docs/cd/E11882_01/server.112/e17118/sql_elements001.htm#i45441
http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/datatype.htm

Varchar2 is (or at least was) capped at 4000 max length in a table. CLOB's can be longer than this. Most of my knowledge is oracle 7/8/9 so maybe VARCHAR2 can be longer than 4000 now. But back in the day you had to use CLOBs