Inserting and retrieving ampersand(&) in Oracle

SQL> create table amp_test (no number,value varchar2(100));

Table created.

SQL> insert into amp_test values (1,'hyd');

1 row created.

SQL> insert into amp_test values (2,'at&t');
Enter value for t:
old   1: insert into amp_test values (2,'at&t')
new   1: insert into amp_test values (2,'at')

1 row created.

SQL> commit;

Commit complete.

SQL> select * from amp_test;

        NO VALUE
---------- ----------------------------------------------------------------------------------------------------
         1 hyd
         2 at

SQL>  insert into amp_test values (3,'at"&"t');

1 row created.

SQL> select * from amp_test;

        NO VALUE
---------------------------------------
         1 hyd
         2 at
         3 at"&"t

SQL> insert into amp_test values (4,'at'||'&'||'t');

1 row created.

SQL> select * from amp_test;

        NO VALUE
-----------------------------------------------------
         1 hyd
         2 at
         3 at"&"t
         4 at&t
SQL> SELECT NO, REPLACE (VALUE, '&', CHR (ASCII ('&')) || 'amp;') as value FROM amp_test;

   NO VALUE1

   2 at&t
  
   PLSQL:
---------------------------------
BEGIN
  IF v_ats = 'AT'||CHR (ASCII ('&'))|| 'T'  THEN
   logic...
 END IF; 
END;
/