????????????У??????????????????????????????????????????????????
???????MYSQL??????????
????MYSQL???????????????????limit??????????????????????????????÷????????м?????????????????? limit m??n?????
?????????????????????limit????÷????
????// limit m ?? n????? m ????????????? n ??????
????1???????????????select * from tablename limit m??n;
????// limit m ?? n??m ????????????????????? 0 ?? ???
????2???????????????
????// ??490000????10??
????a.  select * from tablename where id>=(select id from tablename limit 490000??1) limit 10 ;
????b.  select * from tablename limit 490000??10 ;
????a ?????? b?????
????????DB2??????????
????DB2??????????????? rownumber() over() ??????????????￡?
????select * from(select ???1?????2...rownumber() over(order by id desc) as rn from tablename where...) as t1
????where t1.rn between m and n / t1.rn >m and t1.rn <= n;
????????ORACLE??????????
????ORACLE???????????rownum??????rownumber() over()???????????￡?
????1??rownum?????--??????--??? n ?? m??????
????a. ?????????????ROWNUM <= m ??????????????????????С?:
????select * from (
????select a.*?? rownum rn from (
????select * from tablename) a
????where rownum <= m)
????where rn >= n
????b.  ?????????????С?
????select * from (
????select a.*?? rownum rn from (
????select * from tablename) a)
????where rn between n and m
????//????????????￡?a??????b???????
????2??rownum?????--??????--??? n ?? m??????
????// ?????
????select * from
????(select t.*??rownum rn from mytable t order by t.id) b
????where b.row_num between n and m
????//???????????sql??????? rownum rn?????к???? ???order by ??????????????rn???к?????order by??????????
????// ??????????????????????????????к???????rn???????????????????????
????//??????:????????????
????select * from
????(select a.*?? rownum rn from (select * from tablename order by id)a)b
????where b.rn between n and m
????3??rownum() over()???--?db2???
????select * from(select ???1?????2...rownumber() over(order by id desc) as rn from tablename where...) as t1
????where t1.rn between m and n / t1.rn >m and t1.rn <= n;