Using Mod Function

Write a query to display  Alternate rows 

Answer:

select * from (select empno,ename,rownum  rn from emp) where mod(rn,2) = 1;

or

select * from (select empno,ename,rownum  rn from emp) where mod(rn,2) = 0;

Write a query to display even number rows 1st and odd number second

Answer: 

create table emp_a as select * from emp 

where empno in (7566,7654,7698,7499,7521,7839);

Query

select * from emp_a where mod(empno,2)=0

union all

select * from emp_a where mod(empno,2)=1;

Write a query to display even number rows

Answer:  

select * from  (select empno,ename,rownum  rn from emp) where mod(rn,2) = 0;

Write a query to display odd number rows

Answer:  

select * from  (select empno,ename,rownum  rn from emp) where mod(rn,2) = 1;