row_number() over()函数中，over()里的分组以及排序的执行晚于 where 、group by、 order by 的执行。

#### 1.使用row_number（）函数进行编号，如

``select email,customerID, ROW_NUMBER() over(order by psd) as rows from QT_Customer``

#### 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：

``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：

``````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：

``````with tabs as
(
select ROW_NUMBER() over(partition by customerID  order by totalPrice)
as rows,customerID,totalPrice, DID from OP_Order
)
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：

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。

``````    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
) ``````

#### 6.筛选出客户第一次下的订单。

``````    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 ``````

#### 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。

``````    select
ROW_NUMBER() over(partition by customerID  order by insDT) as rows,
customerID,totalPrice, DID
from OP_Order where insDT>'2011-07-22' ``````