Oracle 11g Release 2

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create table dept(dno number(3) primary key)
create table emp(eno number(3) primary key,dno number(3) references dept)
insert all
into dept values(101)
into dept values(102)
into dept values(103)
into dept values(104)
into dept values(105)
select * from dual
5 rows affected

create or replace view  emp_cnt
 AS
 select dno,count(eno) cnt from emp 
group by dno;
BEGIN
insert into emp values(1,101);
insert into emp values(2,101);
insert into emp values(3,102);
END;
/
1 rows affected

select * from  emp_cnt;


DNO
CNT


102
1

101
2