Use dbms_lob.getlength and dbms_lob.substr with blob type column : DBMS_LOB « System Packages « Oracle PL/SQL Tutorial

SQL>
SQL> create table demo
  2  ( id           int primary key,
  3    theBlob      blob
  4  )
  5  /

Table created.

SQL>
SQL> select id, dbms_lob.getlength(theBlob) len, clean(theBlob) piece, dbms_lob.substr(theBlob,40,1) raw_data
  2  from demo
  3  where id =1
  4  /

no rows selected

SQL> drop table demo;

Table dropped.

31.12.DBMS_LOB
	31.12.1.	DBMS_LOB Package
	31.12.2.	Print clob data out
	31.12.3.	Use dbms_lob.getlength to get the length of a clob data
	31.12.4.	Show Java source file
	31.12.5.	Use dbms_lob package to deal with clob data
	31.12.6.	Use dbms_lob.getlength and dbms_lob.substr with blob type column
	31.12.7.	Use dbms_lob.substr to get part of clob data
	31.12.8.	DBMS_LOB.READ
	31.12.9.	Load a file