SQL> ed
Wrote file afiedt.buf

  1  declare
  2  x1 varchar2(1):='a';
  3  x2 varchar2(1);
  4  x3 varchar2(1);
  5  begin
  6  x2:=x1;
  7  x3:=x2;
  8  dbms_output.put_line('the value of x1 : '||x1);
  9  dbms_output.put_line('the value of x2 : '||x2);
 10  dbms_output.put_line('the value of x2 : '||x2);
 11* end;
 12  /
the value of x1 : a
the value of x2 : a
the value of x2 : a

PL/SQL procedure successfully completed.