ROW NUMBER OVER 函式用法詳解

2021-10-06 15:00:19 字數 3414 閱讀 3678

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()函式時候,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:表資料:

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資料

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歲資料,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,其實就表明了 over(order by salary desc) 是在where age between and 後執行的

例二:1.使用row_number()函式進行編號,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,給每條資料進行編號。

2.在訂單中按**的公升序進行排序,並給每條記錄進行排序**如下:

select did,customerid,totalprice,row_number() over(order by totalprice) as rows from op_order

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

select row_number() over(partition by customerid  order by totalprice)

as rows,customerid,totalprice, did from op_order

4.統計每乙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.統計每乙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.然後利用子查詢查詢出每乙個客戶購買時的最小**。

3.根據查詢出每乙個客戶的最小**來查詢相應的記錄。

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.注意:在使用over等開窗函式時,over裡頭的分組及排序的執行晚於「where,group by,order by」的執行。

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