sql ROW_NUMBER()與OVER()方法案例詳解

語法格式:row_number() over(partition by 分組列 order by 排序列 desc)

row_number() over()分組排序功能:

在使用 row_number() over()函數時候,over()裡頭的分組以及排序的執行晚於 where 、group by、  order by 的執行。

例一:

表數據:

create table TEST_ROW_NUMBER_OVER(
       id varchar(10) not null,
       name varchar(10) null,
       age varchar(10) null,
       salary int null
);
select * from TEST_ROW_NUMBER_OVER t;
 
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(1,'a',10,8000);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(1,'a2',11,6500);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(2,'b',12,13000);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(2,'b2',13,4500);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(3,'c',14,3000);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(3,'c2',15,20000);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(4,'d',16,30000);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(5,'d2',17,1800);

一次排序:對查詢結果進行排序(無分組)

select id,name,age,salary,row_number()over(order by salary desc) rn
from TEST_ROW_NUMBER_OVER t

結果:

進一步排序:根據id分組排序

select id,name,age,salary,row_number()over(partition by id order by salary desc) rank
from TEST_ROW_NUMBER_OVER t

結果:

 再一次排序:找出每一組中序號為一的數據

select * from(select id,name,age,salary,row_number()over(partition by id order by salary desc) rank
from TEST_ROW_NUMBER_OVER t)
where rank <2

結果:

排序找出年齡在13歲到16歲數據,按salary排序

select id,name,age,salary,row_number()over(order by salary desc)  rank
from TEST_ROW_NUMBER_OVER t where age between '13' and '16'

結果:結果中 rank 的序號,其實就表明瞭 over(order by salary desc) 是在where age between and 後執行的

例二:

1.使用row_number()函數進行編號,如

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

原理:先按psd進行排序,排序完後,給每條數據進行編號。

2.在訂單中按價格的升序進行排序,並給每條記錄進行排序代碼如下:

select DID,customerID,totalPrice,ROW_NUMBER() over(order by totalPrice) as rows from OP_Order

3.統計出每一個各戶的所有訂單並按每一個客戶下的訂單的金額 升序排序,同時給每一個客戶的訂單進行編號。這樣就知道每個客戶下幾單瞭:

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

4.統計每一個客戶最近下的訂單是第幾次下的訂單:

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 '下單次數',customerID from tabs 
group by customerID 

5.統計每一個客戶所有的訂單中購買的金額最小,而且並統計改訂單中,客戶是第幾次購買的:

思路:利用臨時表來執行這一操作。

1.先按客戶進行分組,然後按客戶的下單的時間進行排序,並進行編號。

2.然後利用子查詢查找出每一個客戶購買時的最小價格。

3.根據查找出每一個客戶的最小價格來查找相應的記錄。

    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.篩選出客戶第一次下的訂單。

思路。利用rows=1來查詢客戶第一次下的訂單記錄。

    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.註意:在使用over等開窗函數時,over裡頭的分組及排序的執行晚於“where,group by,order by”的執行。

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

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