SQL> create table mje (a int, b varchar(10) null default null);
SQLRowCount returns -1
SQL> insert into mje (a,b) values(1,'fred');
SQLRowCount returns 1
SQL> insert into mje (a,b) values(2, '');
SQLRowCount returns 1
SQL> insert into mje (a) values(3);
SQLRowCount returns 1
SQL> select * from mje;
+------------+-----------+
| a          | b         |
+------------+-----------+
| 1          | fred      |
| 2          |           |
| 3          |           |
+------------+-----------+
SQLRowCount returns -1
3 rows fetched