语法：ROW_NUMBER()
OVER(PARTITION
BY
COLUMN
ORDER
BY
COLUMN)
简单的说row_number()从1开始，为每一条分组记录返回一个数字，这里的ROW_NUMBER()
OVER
(ORDER
BY
xlh
DESC)
是先把xlh列降序，再为降序以后的没条xlh记录返回一个序号。
示例：
xlh
row_num
1700
1
1500
2
1085
3
710
4
row_number()
OVER
(PARTITION
BY
COL1
ORDER
BY
COL2)
表示根据COL1分组，在分组内部根据
COL2排序，而此函数计算的值就表示每组内部排序后的顺序编号（组内连续的唯一的)
实例：
初始化数据
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)
数据显示为
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：根据部门分组，显示每个部门的工资等级
预期结果：
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脚本：
SELECT
*,
Row_Number()
OVER
(partition
by
deptid
ORDER
BY
salary
desc)
rank
FROM
employee
标签：row
