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oracle 分页sql 话语比较

热度:103   发布时间:2016-05-05 15:06:20.0
oracle 分页sql 语句比较

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

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