oracleclob转blob

CREATE OR REPLACE FUNCTION C2B (b IN CLOB default empty_clob())

   RETURN BLOB

-- typecasts BLOB to CLOB (binary conversion)

IS

   res            BLOB;

   b_len          number  := dbms_lob.getlength(b) ;

   dest_offset1   NUMBER  := 1;

   src_offset1    NUMBER  := 1;

   amount_c       INTEGER := DBMS_LOB.lobmaxsize;

   blob_csid      NUMBER  := DBMS_LOB.default_csid;

   lang_ctx       INTEGER := DBMS_LOB.default_lang_ctx;

   warning        INTEGER;

BEGIN

   if  b_len  > 0  then

   DBMS_LOB.createtemporary (res, TRUE);

   DBMS_LOB.OPEN (res, DBMS_LOB.lob_readwrite);

   DBMS_LOB.convertToBlob (res,

                           b,

                           amount_c,

                           dest_offset1,

                           src_offset1,

                           blob_csid,

                           lang_ctx,

                           warning

                          );

 else

   select   empty_blob()  into  res  from  dual ;

  end if ;

   RETURN res;                                             -- res is OPEN here

END C2B;