sqlServer使用ROW_NUMBER时不排序
--1.看到NHibernate是这样写的分页,感觉写起来比较容易理解(应该不会有效率问题吧?) --with只是定一个别名? [sql] 代码如下 with query as (selectROW_NUMBER() over(order by (select 0)) AS ROWNUM, * FROM Product) select * from query where ROWNUM BET
--1.看到NHibernate是这样写的分页,感觉写起来比较容易理解(应该不会有效率问题吧?)
--with只是定一个别名?
[sql]
代码如下
with query as (select ROW_NUMBER() over(order by (select 0)) AS ROWNUM, * FROM Product)
select * from query where ROWNUM BETWEEN 5 AND 10
--2.ROW_NUMBER必须指写over (order by **),有时我根本就不想排序,想按原始顺序(排序也是要时间的嘛)
--方法就是:
代码如下
select ROW_NUMBER() over(order by (select 0)) AS ROWNUM,* FROM Product
排序 就是 :
代码如下
select Row_number() over(order by Oper_Date desc) AS ROWNUM,* FROM Product
接着我们来看一个实例ROW_NUMBER排序实例
1使用row_number()函数进行编号:如
代码如下
select email,customerID, ROW_NUMBER() over(order by psd) as rows from QT_Customer
原理:先按psd进行排序,排序完后,给每条数据进行编号。
2.在订单中按价格的升序进行排序,并给每条记录进行排序
代码如下:
代码如下
select DID,customerID,totalPrice,ROW_NUMBER() over(order by totalPrice) as rows from OP_Order
3.统计出每一个各户的所有订单并按每一个客户下的订单的金额 升序排序,同时给每一个客户的订单进行编号。这样就知道每个客户下几单了。
如图:
代码如下:
代码如下
select ROW_NUMBER() over(partition by customerID order by totalPrice) as rows,customerID,totalPrice, DID from OP_Order
4.统计每一个客户最近下的订单是第几次下的订单。
代码如下:
代码如下
1 with tabs as
2 (
3 select ROW_NUMBER() over(partition by customerID order by totalPrice) as rows,customerID,totalPrice, DID from OP_Order
4 )
5
6 select MAX(rows) as '下单次数',customerID from tabs group by customerID
5.统计每一个客户所有的订单中购买的金额最小,而且并统计改订单中,客户是第几次购买的。
如图:
上图:rows表示客户是第几次购买。
思路:利用临时表来执行这一操作
1.先按客户进行分组,然后按客户的下单的时间进行排序,并进行编号。
2.然后利用子查询查找出每一个客户购买时的最小价格。
3.根据查找出每一个客户的最小价格来查找相应的记录。
代码如下
with tabs as
(
select ROW_NUMBER() over(partition by customerID order by insDT) as rows,customerID,totalPrice, DID from OP_Order
)
select * from tabs
where totalPrice in
(
select MIN(totalPrice)from tabs group by customerID
)
5.筛选出客户第一次下的订单。
思路。利用rows=1来查询客户第一次下的订单记录。
with tabs as
(
select ROW_NUMBER() over(partition by customerID order by insDT) as rows,* from OP_Order
)
select * from tabs where rows = 1
select * from OP_Order
6.rows_number()可用于分页
思路:先把所有的产品筛选出来,然后对这些产品进行编号。然后在where子句中进行过滤。
7.注意:在使用over等开窗函数时,over里头的分组及排序的执行晚于“where,group by,order by”的执行。
如下代码:
代码如下
1 select
2 ROW_NUMBER() over(partition by customerID order by insDT) as rows,
3 customerID,totalPrice, DID
4 from OP_Order where insDT>'2011-07-22'

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