hive开窗函数运用案例

1.数据
s1,201801,A
s1,201802,A
s1,201803,C
s1,201804,A
s1,201805,A
s1,201806,A
s2,201801,A
s2,201802,B
s2,201803,C
s2,201804,A
s2,201805,D
s2,201806,A
s3,201801,C
s3,201802,A
s3,201803,A
s3,201804,A
s3,201805,B
s3,201806,A
2.建表
create table if not exists student(name string,month string,degree string)
row format delimited
fields terminated by ','
;
load data local inpath '/root/stu.txt' into table student;
3.现要查询表中连续三个月以上degree均为A的记录？
select
    a1.name,
    a1.month,
    a1.degree
from
(
    select
        name,
        month,
        degree,
        sum(if(degree = 'A', 1, 0)) OVER(PARTITION BY name ORDER BY month ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) AS score1,
        sum(if(degree = 'A', 1, 0)) OVER(PARTITION BY name ORDER BY month ROWS BETWEEN 1 PRECEDING AND 1 following) AS score2,
        sum(if(degree = 'A', 1, 0)) OVER(PARTITION BY name ORDER BY month ROWS BETWEEN  CURRENT ROW AND 2 following) AS score3
    from student
) as a1
where
    a1.score1 = 3 or
    a1.score2 = 3 or
    a1.score3 = 3
结果：
s1      201804  A
s1      201805  A
s1      201806  A
s3      201802  A
s3      201803  A
s3      201804  A