说说oracle分页的sql语句,分排序和不排序两种。
?当结果集不需要进行排序时,每页显示条数为:rowPerPage,当前页数为:currentPage。
?1、?相对来说,这种查询速度会快一些,因为当currentPage小时,嵌套语句查询的结果集小。但当currentPage 变大时,查询速度会慢慢变慢。当结果集很大时,查询第一页跟最后一页的速度会有明显变化。(倾向用这种!)
Java代码
select?*?
from (??
select?rownum?r,??field1,field2?
from?table_name?
where?rownum?<=?currentPage?*?rowPerPage
)???
Where? r?>?(currentPage-1)?*?rowPerPage???
select * from(
select rownum r,? field1,field2 from table_name where rownum <= currentPage * rowPerPage
)
where r > (currentPage-1) * rowPerPage
?2、相对来说,这种查询速度会慢一些,无论当currentPage大小,嵌套语句查询的结果集都是一样多的,都是整个结果集。但是,当结果集很大时,查询第一页跟最后一页的速度不会有明显变化。
? Java代码 ?
select *
from?? (?
?????? select rownum r,? field1,field2
?????? from table_name??
??? )??
where r? > (currentPage-1) * rowPerPage
and? r <= currentPage * rowPerPage?
select * from(
select rownum r,? field1,field2 from table_name
)
where r? > (currentPage-1) * rowPerPage? and? r <= currentPage * rowPerPage
当需要进行排序时,以第一种方式进行示例如下:
?Java代码 ?
select *
from??? (?
??? select rownum r, a.*
??? from (?
??????? select? field1,field2
??????? from table_name
??????? order by field1??
??? ) a
??? where rownum <= currentPage * rowPerPage?
)
where r > (currentPage-1) * rowPerPage? ?
select * from(
select rownum r, a.* from (
select? field1,field2 from table_name order by field1
) a where rownum <= currentPage * rowPerPage
) where r > (currentPage-1) * rowPerPage