开窗函数结构：
分析函数+窗口子句
窗口子句
over(partition by ** order by ** rows between ** and **)
其中between ** and ** 之间可以填
| 起始 | 结束 | 解释 |
|---|---|---|
| unbounded preceding | current row | 从第一行到当前行，这是默认的情况 |
| 3 preceding | current row | 从向前3行到当前行 |
| 3 preceding | 3 following | 当前行，向前3行，向后3行 |
| current row | unbounded following | 从当前行到后面 |
分析函数包括
| 分析函数 | 用法 |
|---|---|
| sum(列名) | 有order by 的时候，计算的是分区排序后一个个叠加的值，不加order by 则为分区内的综合 |
| min(列名)、max(列名)、avg（列名） | 与order by 有关 |
| count（列名） | 与order by 有关 |
| row_number() | 从1开始，按照顺序生成分组内记录的序列1，2，3，4，5. |
| rank() | 生成数据项在分组内的排名，排名相等会在名次中留下空位 1，2，3，3，5 ,先order by |
| dense_rank() | 生成数据项在分组内的排名，排名相等不会在名次中留下空位 1，2，3，3，4,先order by |
| ntile(n) | 将分组数据按照顺序切分成n片，返回当前切片值 1，2，…，n；切片不均匀，增加第一个切片分分布，如7行分成3份，则返回的切片值为1，1，1，2，2，3，3；不支持rows between,先order by |
| cum_dist() | 返回小于等于当前值的行数/分组内总行数,先order by |
| percent_rank() | （分组内当前行的rank值-1）/（分组内总行数-1）,先order by |
| lag(列名,向上n行，default 值) | 返回向上第n行的值，没有的话返回默认值或者null |
| lead(列名,向下n行，default 值) | 返回向下第n行的值，没有的话返回默认值或者null |
| first_value(列名) | 取分组内排序后，截至到当前行的第一个值，与order by 有关，与rows between 有关 |
| last_value(列名) | 取分组排序后，截至到当前行的最后一个值，与order by 有关，与rows between 有关 |
练习1
创建表
-- CREATE TABLE IF NOT EXISTS student_scores(
-- id INT,
-- studentId INT,
-- language INT,
-- math INT,
-- english INT,
-- classId STRING,
-- departmentId STRING
-- );
插入数据
-- 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');
count()
SELECT studentid,math,departmentid,classid,
count(math) over() as count1,
count(math) over(PARTITION BY classid) as count2,
count(math) OVER(PARTITION BY classid ORDER BY math ) as count3,
count(math) over(PARTITION BY classid ORDER BY math ROWS BETWEEN 1 PRECEDING and 2 FOLLOWING) as count4
FROM student_scores WHERE departmentid='department1'
解释：对于某一行，count1统计所有的行数，count2统计不同classid的行数，count3统计当前classid排序后小于等于当前值的行数，count4统计前一行后两行、当前行的总行数（以实际行数为准）
sum()
SELECT studentid,math,departmentid,classid,
sum(math) OVER() as sum1,
sum(math) over(PARTITION BY classid) as sum2,
sum(math) over(PARTITION BY classid order by math) as sum3,
sum(math) over(PARTITION BY classid ORDER BY math ROWS BETWEEN 1 PRECEDING AND 2 FOLLOWING) as sum4
FROM student_scores
WHERE departmentid='department1'
min()
SELECT studentid,math,departmentid,classid,
min(math) over() as min1,
min(math) OVER(PARTITION BY classid) as min2,
min(math) OVER(PARTITION BY classid order by classid) as min3,
min(math) OVER(PARTITION BY classid order by classid ROWS BETWEEN 1 PRECEDING AND 2 FOLLOWING) as min4
FROM student_scores
where departmentid='department1'
max()
SELECT studentid,math,departmentid,classid,
max(math) over() as max1,
max(math) over(PARTITION BY classid) as max2,
max(math) over(PARTITION BY classid order by math) as max3,
max(math) over(PARTITION BY classid order by math ROWS BETWEEN 1 PRECEDING and 2 FOLLOWING) as max4
FROM student_scores
where departmentid='department1'
avg()
SELECT studentid,math,departmentid,classid,
round(avg(math) over(),2) as max1,
round(avg(math) over(PARTITION BY classid) ,2) as max2,
round(avg(math) over(PARTITION BY classid order by math) ,2) as max3,
round(avg(math) over(PARTITION BY classid order by math ROWS BETWEEN 1 PRECEDING and 2 FOLLOWING) ,2) as max4
FROM student_scores
where departmentid='department1'
first_value()
SELECT studentid,math,departmentid,classid,
first_value(math) over() as first_value1,
first_value(math) OVER(PARTITION BY classid) as first_value2,
first_value(math) OVER(PARTITION BY classid ORDER BY math) as first_value3,
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'
last_value()
SELECT studentid,math,departmentid,classid,
last_value(math) over() as last_value1,
last_value(math) OVER(PARTITION BY classid) as last_value2,
last_value(math) OVER(PARTITION BY classid ORDER BY math) as last_value3,
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'
lag()
SELECT studentid,math,departmentid,classid,
lag(math,2,60) over(PARTITION BY classid order by math) as lag1,
lag(math,2) over(PARTITION BY classid order by math) as lag2
FROM student_scores
where departmentid='department1'
lead()
SELECT studentid,math,departmentid,classid,
lead(math,2,60) over(PARTITION BY classid order by math) as lead1,
lead(math,2) over(PARTITION BY classid order by math) as lead2
FROM student_scores
where departmentid='department1'
cume_dist()
SELECT studentid,math,departmentid,classid,
round(cume_dist() over(order by math),2) as cum_dist1,
round(cume_dist() OVER(order by math desc) ,2)as cum_dist2,
round(cume_dist() OVER(PARTITION BY classid order by math desc),2) as cum_dist3
FROM student_scores
where departmentid='department1'
rank()
SELECT studentid,math ,
rank() OVER(ORDER BY math) as rank1,
rank() OVER(PARTITION BY departmentid ORDER BY math) as rank2,
rank() over(PARTITION BY departmentid,classid ORDER BY math) as rank3
FROM student_scores
dense_rank()
SELECT studentid,math ,
dense_rank() OVER(ORDER BY math) as dense_rank1,
dense_rank() OVER(PARTITION BY departmentid ORDER BY math) as dense_rank2,
dense_rank() over(PARTITION BY departmentid,classid ORDER BY math) as dense_rank3
FROM student_scores
row_number()
SELECT studentid,departmentid,classid,math,
row_number() over(PARTITION BY departmentid,classid ORDER BY math) as row_number
FROM student_scores
percent_rank()
SELECT studentid,departmentid,classid,math,
row_number() over(PARTITION BY departmentid,classid ORDER BY math) as row_number1,
percent_rank() OVER(PARTITION BY departmentid,classid ORDER BY math) as percent_rank1
FROM student_scores
ntile(n)
SELECT studentid,math,
ntile(2) over(PARTITION BY departmentid order by math) as ntile1,
ntile(3) over(PARTITION BY departmentid order by math) as ntile2
FROM student_scores
练习2
练习2
创建并插入数据
-- INSERT INTO hivewindowtest1 VALUES
-- ('tony','2017-01-02',15),
-- ('jack','2017-02-03',23),
-- ('tony','2017-01-04',29),
-- ('jack','2017-01-05',46),
-- ('jack','2017-04-06',42),
-- ('tony','2017-01-07',50),
-- ('jack','2017-01-08',55),
-- ('mart','2017-04-08',62),
-- ('mart','2017-04-09',68),
-- ('neil','2017-05-10',12),
-- ('mart','2017-04-11',75),
-- ('neil','2017-06-12',80),
-- ('mart','2017-04-13',94);
– （1）查询在2017年4月份购买过的顾客及总人数
SELECT name,count(*) over()
FROM hivewindowtest1
where substring(orderdate,1,7)='2017-04'
group by name
– （2）查询顾客的购买明细及月购买总额
SELECT *,
sum(cost) OVER(PARTITION BY name,month(orderdate))
FROM hivewindowtest1
– （3）上述的场景,要将cost按照日期进行累加
SELECT *,
sum(cost) OVER(PARTITION BY name ORDER BY orderdate)
FROM hivewindowtest1
– （4）查询顾客上次的购买时间
SELECT *,
lag(orderdate,1) OVER(PARTITION BY name ORDER BY orderdate) as lastbuytime
FROM hivewindowtest1
– （5）查询前20%时间的订单信息
SELECT name,orderdate,cost from
(SELECT name,orderdate,cost,
ntile(5) over(ORDER BY orderdate) as hh
FROM hivewindowtest1) TT
where TT.hh=1
来源：https://blog.csdn.net/sinat_37386947/article/details/100154563