Using Clustures in Oracle

create cluster c1(deptno number(2));

create cluster c2( empno number(4));

create table dept(deptno number(2) primary key,
dname varchar2(20), loc varchar2(20))
cluster c1(deptno);

create table emp
(empno number(4) primary key,
 ename varchar2(20),job varchar2(20),
sal number(12,2),comm number(12,2),
deptno number(2) references dept)
cluster c1(deptno),c2(empno);

create table incr (empno number(4) references emp,
amt number(10,2)) cluster c2(empno);

create index c1_idx on cluster c1;

create index c2_idx on cluster c2;