Hive 开窗函数 | 易学教程

转自：https://blog.csdn.net/wangpei1949/article/details/81437574

开窗函数

普通的聚合函数聚合的行集是组,开窗函数聚合的行集是窗口。因此,普通的聚合函数每组(Group by)只返回一个值，而开窗函数则可为窗口中的每行都返回一个值。简单理解，就是对查询的结果多出一列，这一列可以是聚合值，也可以是排序值。开窗函数一般分为两类,聚合开窗函数和排序开窗函数。

测试数据

-- 建表
create table student_scores(
id int,
studentId int,
language int,
math int,
english int,
classId string,
departmentId string
);
-- 写入数据
insert into table student_scores values
(1,111,68,69,90,'class1','department1'),
(2,112,73,80,96,'class1','department1'),
(3,113,90,74,75,'class1','department1'),
(4,114,89,94,93,'class1','department1'),
(5,115,99,93,89,'class1','department1'),
(6,121,96,74,79,'class2','department1'),
(7,122,89,86,85,'class2','department1'),
(8,123,70,78,61,'class2','department1'),
(9,124,76,70,76,'class2','department1'),
(10,211,89,93,60,'class1','department2'),
(11,212,76,83,75,'class1','department2'),
(12,213,71,94,90,'class1','department2'),
(13,214,94,94,66,'class1','department2'),
(14,215,84,82,73,'class1','department2'),
(15,216,85,74,93,'class1','department2'),
(16,221,77,99,61,'class2','department2'),
(17,222,80,78,96,'class2','department2'),
(18,223,79,74,96,'class2','department2'),
(19,224,75,80,78,'class2','department2'),
(20,225,82,85,63,'class2','department2');

聚合开窗函数

1.count开窗函数

-- count 开窗函数

select studentId,math,departmentId,classId,
-- 以符合条件的所有行作为窗口
count(math) over() as count1,
 -- 以按classId分组的所有行作为窗口
count(math) over(partition by classId) as count2,
 -- 以按classId分组、按math排序的所有行作为窗口
count(math) over(partition by classId order by math) as count3,
 -- 以按classId分组、按math排序、按 当前行+往前1行+往后2行的行作为窗口
count(math) over(partition by classId order by math rows between 1 preceding and 2 following) as count4
from student_scores where departmentId='department1';

结果
studentid   math    departmentid    classid count1  count2  count3  count4
111         69      department1     class1  9       5       1       3
113         74      department1     class1  9       5       2       4
112         80      department1     class1  9       5       3       4
115         93      department1     class1  9       5       4       3
114         94      department1     class1  9       5       5       2
124         70      department1     class2  9       4       1       3
121         74      department1     class2  9       4       2       4
123         78      department1     class2  9       4       3       3
122         86      department1     class2  9       4       4       2

结果解释:
studentid=115,count1为所有的行数9,count2为分区class1中的行数5,count3为分区class1中math值<=93的行数4,
count4为分区class1中math值向前+1行向后+2行(实际只有1行)的总行数3。

2.sum开窗函数

-- sum开窗函数

select studentId,math,departmentId,classId,
-- 以符合条件的所有行作为窗口
sum(math) over() as sum1,
-- 以按classId分组的所有行作为窗口
sum(math) over(partition by classId) as sum2,
 -- 以按classId分组、按math排序后、按到当前行(含当前行)的所有行作为窗口
sum(math) over(partition by classId order by math) as sum3,
 -- 以按classId分组、按math排序后、按当前行+往前1行+往后2行的行作为窗口
sum(math) over(partition by classId order by math rows between 1 preceding and 2 following) as sum4
from student_scores where departmentId='department1';

结果
studentid   math    departmentid    classid sum1    sum2    sum3    sum4
111         69      department1     class1  718     410     69      223
113         74      department1     class1  718     410     143     316
112         80      department1     class1  718     410     223     341
115         93      department1     class1  718     410     316     267
114         94      department1     class1  718     410     410     187
124         70      department1     class2  718     308     70      222
121         74      department1     class2  718     308     144     308
123         78      department1     class2  718     308     222     238
122         86      department1     class2  718     308     308     164

结果解释:
    同count开窗函数

3.min开窗函数

-- min 开窗函数

select studentId,math,departmentId,classId,
-- 以符合条件的所有行作为窗口
min(math) over() as min1,
-- 以按classId分组的所有行作为窗口
min(math) over(partition by classId) as min2,
 -- 以按classId分组、按math排序后、按到当前行(含当前行)的所有行作为窗口
min(math) over(partition by classId order by math) as min3,
 -- 以按classId分组、按math排序后、按当前行+往前1行+往后2行的行作为窗口
min(math) over(partition by classId order by math rows between 1 preceding and 2 following) as min4
from student_scores where departmentId='department1';

结果
studentid   math    departmentid    classid min1    min2    min3    min4
111         69      department1     class1  69      69      69      69
113         74      department1     class1  69      69      69      69
112         80      department1     class1  69      69      69      74
115         93      department1     class1  69      69      69      80
114         94      department1     class1  69      69      69      93
124         70      department1     class2  69      70      70      70
121         74      department1     class2  69      70      70      70
123         78      department1     class2  69      70      70      74
122         86      department1     class2  69      70      70      78

结果解释:
    同count开窗函数

4.max开窗函数

-- max 开窗函数

select studentId,math,departmentId,classId,
-- 以符合条件的所有行作为窗口
max(math) over() as max1,
-- 以按classId分组的所有行作为窗口
max(math) over(partition by classId) as max2,
 -- 以按classId分组、按math排序后、按到当前行(含当前行)的所有行作为窗口
max(math) over(partition by classId order by math) as max3,
 -- 以按classId分组、按math排序后、按当前行+往前1行+往后2行的行作为窗口
max(math) over(partition by classId order by math rows between 1 preceding and 2 following) as max4
from student_scores where departmentId='department1';

结果
studentid   math    departmentid    classid max1    max2    max3    max4
111         69      department1     class1  94      94      69      80
113         74      department1     class1  94      94      74      93
112         80      department1     class1  94      94      80      94
115         93      department1     class1  94      94      93      94
114         94      department1     class1  94      94      94      94
124         70      department1     class2  94      86      70      78
121         74      department1     class2  94      86      74      86
123         78      department1     class2  94      86      78      86
122         86      department1     class2  94      86      86      86

结果解释:
    同count开窗函数

5.avg开窗函数

-- avg 开窗函数

select studentId,math,departmentId,classId,
-- 以符合条件的所有行作为窗口
avg(math) over() as avg1,
-- 以按classId分组的所有行作为窗口
avg(math) over(partition by classId) as avg2,
 -- 以按classId分组、按math排序后、按到当前行(含当前行)的所有行作为窗口
avg(math) over(partition by classId order by math) as avg3,
 -- 以按classId分组、按math排序后、按当前行+往前1行+往后2行的行作为窗口
avg(math) over(partition by classId order by math rows between 1 preceding and 2 following) as avg4
from student_scores where departmentId='department1';

结果
studentid   math    departmentid    classid avg1                avg2    avg3                avg4
111         69      department1     class1  79.77777777777777   82.0    69.0                74.33333333333333
113         74      department1     class1  79.77777777777777   82.0    71.5                79.0
112         80      department1     class1  79.77777777777777   82.0    74.33333333333333   85.25
115         93      department1     class1  79.77777777777777   82.0    79.0                89.0
114         94      department1     class1  79.77777777777777   82.0    82.0                93.5
124         70      department1     class2  79.77777777777777   77.0    70.0                74.0
121         74      department1     class2  79.77777777777777   77.0    72.0                77.0
123         78      department1     class2  79.77777777777777   77.0    74.0                79.33333333333333
122         86      department1     class2  79.77777777777777   77.0    77.0                82.0

结果解释:
    同count开窗函数

6.first_value开窗函数

返回分区中的第一个值

-- first_value 开窗函数

select studentId,math,departmentId,classId,
-- 以符合条件的所有行作为窗口
first_value(math) over() as first_value1,
-- 以按classId分组的所有行作为窗口
first_value(math) over(partition by classId) as first_value2,
 -- 以按classId分组、按math排序后、按到当前行(含当前行)的所有行作为窗口
first_value(math) over(partition by classId order by math) as first_value3,
 -- 以按classId分组、按math排序后、按当前行+往前1行+往后2行的行作为窗口
first_value(math) over(partition by classId order by math rows between 1 preceding and 2 following) as first_value4
from student_scores where departmentId='department1';

结果
studentid   math    departmentid    classid first_value1    first_value2    first_value3    first_value4
111         69      department1     class1  69              69              69              69
113         74      department1     class1  69              69              69              69
112         80      department1     class1  69              69              69              74
115         93      department1     class1  69              69              69              80
114         94      department1     class1  69              69              69              93
124         70      department1     class2  69              74              70              70
121         74      department1     class2  69              74              70              70
123         78      department1     class2  69              74              70              74
122         86      department1     class2  69              74              70              78

结果解释:
    studentid=124 first_value1:第一个值是69,first_value2:classId=class1分区 math的第一个值是69

7.last_value开窗函数

返回分区中的第一个值

-- last_value 开窗函数

select studentId,math,departmentId,classId,
-- 以符合条件的所有行作为窗口
last_value(math) over() as last_value1,
-- 以按classId分组的所有行作为窗口
last_value(math) over(partition by classId) as last_value2,
 -- 以按classId分组、按math排序后、按到当前行(含当前行)的所有行作为窗口
last_value(math) over(partition by classId order by math) as last_value3,
 -- 以按classId分组、按math排序后、按当前行+往前1行+往后2行的行作为窗口
last_value(math) over(partition by classId order by math rows between 1 preceding and 2 following) as last_value4
from student_scores where departmentId='department1';

结果
studentid   math    departmentid    classid last_value1 last_value2 last_value3 last_value4
111         69      department1     class1  70          93          69          80
113         74      department1     class1  70          93          74          93
112         80      department1     class1  70          93          80          94
115         93      department1     class1  70          93          93          94
114         94      department1     class1  70          93          94          94
124         70      department1     class2  70          70          70          78
121         74      department1     class2  70          70          74          86
123         78      department1     class2  70          70          78          86
122         86      department1     class2  70          70          86          86

8.lag开窗函数

lag(col,n,default) 用于统计窗口内往上第n个值。

　　 col:列名

　　 n:往上第n行

　　 default:往上第n行为NULL时候，取默认值,不指定则取NULL

-- lag 开窗函数

select studentId,math,departmentId,classId,
 --窗口内 往上取第二个 取不到时赋默认值60
lag(math,2,60) over(partition by classId order by math) as lag1,
 --窗口内 往上取第二个 取不到时赋默认值NULL
lag(math,2) over(partition by classId order by math) as lag2
from student_scores where departmentId='department1';

结果
studentid   math    departmentid    classid lag1    lag2
111         69      department1     class1  60      NULL
113         74      department1     class1  60      NULL
112         80      department1     class1  69      69
115         93      department1     class1  74      74
114         94      department1     class1  80      80
124         70      department1     class2  60      NULL
121         74      department1     class2  60      NULL
123         78      department1     class2  70      70
122         86      department1     class2  74      74

结果解释:
    第3行 lag1:窗口内(69 74 80) 当前行80 向上取第二个值为69
    倒数第3行 lag2:窗口内(70 74) 当前行74 向上取第二个值为NULL

9.lead开窗函数

lead(col,n,default) 用于统计窗口内往下第n个值。

　　 col:列名

　　 n:往下第n行 default:

　　往下第n行为NULL时候，取默认值,不指定则取NULL

-- lead开窗函数

select studentId,math,departmentId,classId,
 --窗口内 往下取第二个 取不到时赋默认值60
lead(math,2,60) over(partition by classId order by math) as lead1,
 --窗口内 往下取第二个 取不到时赋默认值NULL
lead(math,2) over(partition by classId order by math) as lead2
from student_scores where departmentId='department1';

结果
studentid   math    departmentid    classid lead1   lead2
111         69      department1     class1  80      80
113         74      department1     class1  93      93
112         80      department1     class1  94      94
115         93      department1     class1  60      NULL
114         94      department1     class1  60      NULL
124         70      department1     class2  78      78
121         74      department1     class2  86      86
123         78      department1     class2  60      NULL
122         86      department1     class2  60      NULL

结果解释:
    第4行lead1 窗口内向下第二个值为空，赋值60

10.cume_dist开窗函数

计算某个窗口或分区中某个值的累积分布。假定升序排序，则使用以下公式确定累积分布：

　　小于等于当前值x的行数 / 窗口或partition分区内的总行数。其中，x 等于 order by 子句中指定的列的当前行中的值。

-- cume_dist 开窗函数

select studentId,math,departmentId,classId,
-- 统计小于等于当前分数的人数占总人数的比例
cume_dist() over(order by math) as cume_dist1,
-- 统计大于等于当前分数的人数占总人数的比例
cume_dist() over(order by math desc) as cume_dist2,
-- 统计分区内小于等于当前分数的人数占总人数的比例
cume_dist() over(partition by classId order by math) as cume_dist3
from student_scores where departmentId='department1';

结果
studentid   math    departmentid    classid cume_dist1              cume_dist2          cume_dist3
111         69      department1     class1  0.1111111111111111      1.0                 0.2
113         74      department1     class1  0.4444444444444444      0.7777777777777778  0.4
112         80      department1     class1  0.6666666666666666      0.4444444444444444  0.6
115         93      department1     class1  0.8888888888888888      0.2222222222222222  0.8
114         94      department1     class1  1.0                     0.1111111111111111  1.0
124         70      department1     class2  0.2222222222222222      0.8888888888888888  0.25
121         74      department1     class2  0.4444444444444444      0.7777777777777778  0.5
123         78      department1     class2  0.5555555555555556      0.5555555555555556  0.75
122         86      department1     class2  0.7777777777777778      0.3333333333333333  1.0

结果解释:
    第三行:
        cume_dist1=小于等于80的人数为6/总人数9=0.6666666666666666
        cume_dist2=大于等于80的人数为4/总人数9=0.4444444444444444
        cume_dist3=分区内小于等于80的人数为3/分区内总人数5=0.6

排序开窗函数

1.rank开窗函数

rank 开窗函数基于 over 子句中的 order by 确定一组值中一个值的排名。如果存在partition by ,则为每个分区组中的每个值排名。排名可能不是连续的。例如，如果两个行的排名为 1，则下一个排名为 3。

-- rank 开窗函数

select *,
-- 对全部学生按数学分数排序 
rank() over(order by math) as rank1,
-- 对院系 按数学分数排序
rank() over(partition by departmentId order by math) as rank2,
-- 对每个院系每个班级 按数学分数排序
rank() over(partition by departmentId,classId order by math) as rank3
from student_scores;

结果

id  studentid   language    math    english     classid departmentid    rank1   rank2   rank3
1   111         68          69      90          class1  department1     1       1       1
3   113         90          74      75          class1  department1     3       3       2
2   112         73          80      96          class1  department1     9       6       3
5   115         99          93      89          class1  department1     15      8       4
4   114         89          94      93          class1  department1     17      9       5
9   124         76          70      76          class2  department1     2       2       1
6   121         96          74      79          class2  department1     3       3       2
8   123         70          78      61          class2  department1     7       5       3
7   122         89          86      85          class2  department1     14      7       4
15  216         85          74      93          class1  department2     3       1       1
14  215         84          82      73          class1  department2     11      5       2
11  212         76          83      75          class1  department2     12      6       3
10  211         89          93      60          class1  department2     15      8       4
12  213         71          94      90          class1  department2     17      9       5
13  214         94          94      66          class1  department2     17      9       5
18  223         79          74      96          class2  department2     3       1       1
17  222         80          78      96          class2  department2     7       3       2
19  224         75          80      78          class2  department2     9       4       3
20  225         82          85      63          class2  department2     13      7       4
16  221         77          99      61          class2  department2     20      11      5

2.dense_rank开窗函数

dense_rank与rank有一点不同,当排名一样的时候,接下来的行是连续的。如两个行的排名为 1，则下一个排名为 2。

-- dense_rank 开窗函数

select *,
-- 对全部学生按数学分数排序
dense_rank() over(order by math) as dense_rank1,
-- 对院系 按数学分数排序
dense_rank() over(partition by departmentId order by math) as dense_rank2,
-- 对每个院系每个班级 按数学分数排序
dense_rank() over(partition by departmentId,classId order by math) as dense_rank3
from student_scores;

结果:
id  studentid   language    math    english classid departmentid    dense_rank1 dense_rank2 dense_rank3
1   111         68          69      90      class1  department1     1           1           1
3   113         90          74      75      class1  department1     3           3           2
2   112         73          80      96      class1  department1     5           5           3
5   115         99          93      89      class1  department1     10          7           4
4   114         89          94      93      class1  department1     11          8           5
9   124         76          70      76      class2  department1     2           2           1
6   121         96          74      79      class2  department1     3           3           2
8   123         70          78      61      class2  department1     4           4           3
7   122         89          86      85      class2  department1     9           6           4
15  216         85          74      93      class1  department2     3           1           1
14  215         84          82      73      class1  department2     6           4           2
11  212         76          83      75      class1  department2     7           5           3
10  211         89          93      60      class1  department2     10          7           4
12  213         71          94      90      class1  department2     11          8           5
13  214         94          94      66      class1  department2     11          8           5
18  223         79          74      96      class2  department2     3           1           1
17  222         80          78      96      class2  department2     4           2           2
19  224         75          80      78      class2  department2     5           3           3
20  225         82          85      63      class2  department2     8           6           4
16  221         77          99      61      class2  department2     12          9           5

3.ntile开窗函数

将分区中已排序的行划分为大小尽可能相等的指定数量的排名的组，并返回给定行所在的组的排名。

-- ntile 开窗函数

select *,
-- 对分区内的数据分成两组
ntile(2) over(partition by departmentid order by math) as ntile1,
-- 对分区内的数据分成三组
ntile(3) over(partition by departmentid order by math) as ntile2
from student_scores;

结果
id  studentid   language    math    english classid departmentid    ntile1  ntile2
1   111         68          69      90      class1  department1     1       1
9   124         76          70      76      class2  department1     1       1
6   121         96          74      79      class2  department1     1       1
3   113         90          74      75      class1  department1     1       2
8   123         70          78      61      class2  department1     1       2
2   112         73          80      96      class1  department1     2       2
7   122         89          86      85      class2  department1     2       3
5   115         99          93      89      class1  department1     2       3
4   114         89          94      93      class1  department1     2       3
18  223         79          74      96      class2  department2     1       1
15  216         85          74      93      class1  department2     1       1
17  222         80          78      96      class2  department2     1       1
19  224         75          80      78      class2  department2     1       1
14  215         84          82      73      class1  department2     1       2
11  212         76          83      75      class1  department2     1       2
20  225         82          85      63      class2  department2     2       2
10  211         89          93      60      class1  department2     2       2
12  213         71          94      90      class1  department2     2       3
13  214         94          94      66      class1  department2     2       3
16  221         77          99      61      class2  department2     2       3

结果解释:
    第8行
        ntile1:对分区的数据均匀分成2组后，当前行的组排名为2
        ntile2:对分区的数据均匀分成3组后，当前行的组排名为3

4.row_number开窗函数

从1开始对分区内的数据排序。

-- row_number 开窗函数

select studentid,departmentid,classid,math,
-- 对分区departmentid,classid内的数据按math排序
row_number() over(partition by departmentid,classid order by math) as row_number
from student_scores;

结果
studentid   departmentid    classid math    row_number
111         department1     class1  69      1
113         department1     class1  74      2
112         department1     class1  80      3
115         department1     class1  93      4
114         department1     class1  94      5
124         department1     class2  70      1
121         department1     class2  74      2
123         department1     class2  78      3
122         department1     class2  86      4
216         department2     class1  74      1
215         department2     class1  82      2
212         department2     class1  83      3
211         department2     class1  93      4
213         department2     class1  94      5
214         department2     class1  94      6
223         department2     class2  74      1
222         department2     class2  78      2
224         department2     class2  80      3
225         department2     class2  85      4
221         department2     class2  99      5

结果解释:
    同一分区,相同值，不同序。如studentid=213 studentid=214 值都为94 排序为5,6

5.percent_rank开窗函数

计算给定行的百分比排名。可以用来计算超过了百分之多少的人。如360小助手开机速度超过了百分之多少的人。 (当前行的rank值-1)/(分组内的总行数-1)

-- percent_rank 开窗函数

select studentid,departmentid,classid,math,
row_number() over(partition by departmentid,classid order by math) as row_number,
percent_rank() over(partition by departmentid,classid order by math) as percent_rank
from student_scores;

结果
studentid   departmentid    classid math    row_number  percent_rank
111         department1     class1  69      1           0.0
113         department1     class1  74      2           0.25
112         department1     class1  80      3           0.5
115         department1     class1  93      4           0.75
114         department1     class1  94      5           1.0
124         department1     class2  70      1           0.0
121         department1     class2  74      2           0.3333333333333333
123         department1     class2  78      3           0.6666666666666666
122         department1     class2  86      4           1.0
216         department2     class1  74      1           0.0
215         department2     class1  82      2           0.2
212         department2     class1  83      3           0.4
211         department2     class1  93      4           0.6
213         department2     class1  94      5           0.8
214         department2     class1  94      6           0.8
223         department2     class2  74      1           0.0
222         department2     class2  78      2           0.25
224         department2     class2  80      3           0.5
225         department2     class2  85      4           0.75
221         department2     class2  99      5           1.0

结果解释:
    studentid=115,percent_rank=(4-1)/(5-1)=0.75
    studentid=123,percent_rank=(3-1)/(4-1)=0.6666666666666666

来源：https://www.cnblogs.com/jqbai/p/11420186.html

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partition