Convert CLOB to BLOB

I will write a procedure clob_blob_proc which convert description column of test table of type clob to blob. Here is the procedure.

1)Create a Table with Clob Column:
------------------
SQL> create table test(id number, description clob);

Table created.

2)Insert a Value in it:
---------------------
SQL> insert into test values(1,'Hi');

1 row created.

SQL> commit;

Commit complete.
3)Add a Blob Column:
-------------------
SQL> alter table test add description1 BLOB;

Table altered.

4)Run clob_blob_proc Procedure.
----------------------------
SQL> create or replace procedure clob_blob_proc is
v_clob Clob;
v_blob Blob;
v_in Pls_Integer := 1;
v_out Pls_Integer := 1;
v_lang Pls_Integer := 0;
v_warning Pls_Integer := 0;
v_id number(10);
begin
for num in ( select id,description from test)
loop
v_id:=num.id ;
if num.description is null then v_blob:=null;
else v_clob:=num.description;
v_in:=1;
v_out:=1;
dbms_lob.createtemporary(v_blob,TRUE);
DBMS_LOB.convertToBlob(v_blob,v_clob,DBMS_lob.getlength(v_clob),
v_in,v_out,DBMS_LOB.default_csid,v_lang,v_warning);
end if;
update test set description1=v_blob where id=v_id;
end loop;
commit;
end;
/

Procedure created.

SQL> exec tg_task_proc

PL/SQL procedure successfully completed.

SQL> desc test;
Name Null? Type
----------------------------------------- -------- ----------------------------
ID NUMBER
DESCRIPTION CLOB
DESCRIPTION1 BLOB

5) Drop Old Column and Rename New Column:
-----------------------------------------------
SQL> alter table test drop column description;

Table altered.

SQL> desc test;
Name Null? Type
----------------------------------------- -------- ----------------------------
ID NUMBER
DESCRIPTION1 BLOB


SQL> alter table test rename column description1 to description;

Table altered.

6)Test the Result:
-------------------------
SQL> desc test;
Name Null? Type
----------------------------------------- -------- ----------------------------
ID NUMBER
DESCRIPTION BLOB


SQL> select id, UTL_RAW.CAST_TO_VARCHAR2(DBMS_LOB.SUBSTR(description,4000,1)) description from test;

ID Description
---------- --------------
1 Hi

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