select *,ROW_NUMBER() over(partition by deviceID order by RecordDate desc
?
row_number() OVER (PARTITION BY COL1 ORDER BY COL2) 表示根據COL1分組，在分組內部根據 COL2排序，而此函數計算的值就表示每組內部排序后的順序編號（組內連續的唯一的)
實例：
初始化數據
create table employee (empid int ,deptid int ,salary decimal(10,2))
insert into employee values(1,10,5500.00)
insert into employee values(2,10,4500.00)
insert into employee values(3,20,1900.00)
insert into employee values(4,20,4800.00)
insert into employee values(5,40,6500.00)
insert into employee values(6,40,14500.00)
insert into employee values(7,40,44500.00)
insert into employee values(8,50,6500.00)
insert into employee values(9,50,7500.00)
數據顯示為
empid?????? deptid????? salary ----------- ----------- ---------------------------------------
1?????????? 10????????? 5500.00
2?????????? 10????????? 4500.00
3?????????? 20????????? 1900.00
4?????????? 20????????? 4800.00
5?????????? 40????????? 6500.00
6?????????? 40????????? 14500.00
7?????????? 40????????? 44500.00
8?????????? 50????????? 6500.00
9?????????? 50????????? 7500.00
需求：根據部門分組，顯示每個部門的工資等級
預期結果：
empid?????? deptid????? salary????????????????????????????????? rank ----------- ----------- --------------------------------------- --------------------
1?????????? 10????????? 5500.00???????????????????????????????? 1
2?????????? 10????????? 4500.00???????????????????????????????? 2
4?????????? 20????????? 4800.00???????????????????????????????? 1
3?????????? 20????????? 1900.00???????????????????????????????? 2
7?????????? 40????????? 44500.00???????????????????????????????1
6?????????? 40????????? 14500.00???????????????????????????????2
5?????????? 40????????? 6500.00???????????????????????????????? 3
9?????????? 50????????? 7500.00???????????????????????????????? 1
8?????????? 50????????? 6500.00???????????????????????????????? 2
SQL腳本：
SELECT *, Row_Number() OVER (partition by deptid ORDER BY salary desc) rank FROM employee
?
轉自： http://www.cnblogs.com/digjim/archive/2006/09/20/509344.html
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