SQL>
SQL> declare
2 value1 varchar2(100);
3 value2 varchar2(100) := '';
4 value3 varchar2(100) := null;
5 value4 varchar2(100) default null;
6 begin
7 null;
8 dbms_output.put_line( value1 );
9 dbms_output.put_line( value2 );
10 dbms_output.put_line( value3 );
11 dbms_output.put_line( value4 );
12 end;
13 /
PL/SQL procedure successfully completed.
SQL>
SQL>