페이징 (웹)

ex) 페이징 만드는 순서

select name,basicpay from tblInsa; --원본

select name,basicpay from tblInsa

        order by basicpay desc; --원하는 정렬 + 행번호(유효X)

select name,basicpay,rownum from 

(select name,basicpay from tblInsa

                    order by basicpay desc);  --원하는 정렬 > 다시 행번호 할당(from절)

select name, basicpay,rownum as 방금만든행번호, rnum as 아까만든행번호

    from(select name,basicpay,rownum as rnum  from 

(select name,basicpay from tblInsa order by basicpay desc))

                            where rnum between 1 and 10; < where rnum between 11 and 20;>

ex)인구수가 가장 적은 나라 순서대로 3개 가져오기

select * from

(select a.*,rownum as rnum from

(select * from tblCountry    

    where population is not null

        order by population asc) a)

                        where rnum between 1 and 3;

ex)세대별 그룹

select * from

    (select 세대,명,rownum as rnum from

        (select floor(age/10)*10 as 세대,count(*) as 명 from tblAddressBook

            group by floor(age/10) 

                order by count(*) desc))

                    where rnum =3 or rnum =4;    

cf) rownum은 항상 from 절이 실행될 때 새로 만들어진다.