drop materialized view log on salgrade;
drop materialized view log on emp;

CREATE MATERIALIZED VIEW LOG ON emp WITH SEQUENCE, ROWID INCLUDING NEW VALUES;
CREATE MATERIALIZED VIEW LOG ON salgrade WITH SEQUENCE, ROWID INCLUDING NEW VALUES;

create materialized view Mv_emp_sal 
refresh fast on commit 
as
select e.empno, e.ename, e.sal, s.grade, e.rowid, s.rowid
from emp e, salgrade s
where e.sal between s.losal and s.hisal;

create materialized view Mv_emp_sal 
refresh fast on commit 
as
select e.empno, e.ename, e.sal, s.grade, e.rowid as rowidE, s.rowid as rowidS
from emp e, salgrade s
where e.sal between s.losal and s.hisal;