hive行转列

本文介绍了一种使用SQL进行数据整理的方法,通过将学生姓名与各科成绩映射为键值对,实现数据的横向和纵向整合。此外还展示了如何利用CASE WHEN语句获取指定类别下的最高分。

摘要生成于 C知道 ,由 DeepSeek-R1 满血版支持, 前往体验 >

--转成map,再取值

WITH student AS 

SELECT '张三' AS name ,'语文' AS class, 100 AS score FROM system.dual UNION ALL 
SELECT '张三' AS name ,'数学' AS class, 88 AS score FROM system.dual UNION ALL 
SELECT '李四' AS name ,'语文' AS class, 98 AS score FROM system.dual UNION ALL 
SELECT '李四' AS name ,'数学' AS class, 99 AS score FROM system.dual 

WITH tb AS 

SELECT 
name, 
str_to_map(CONCAT_WS(',',collect_list(concat(class,':',score))),',',':') as kv 
FROM STUDENT GROUP BY name 

SELECT name AS name,map_values(kv)[0] AS '语文',map_values(kv)[1] AS '数学' FROM tb; 

--CASE WHEN 方式

WITH student AS 

SELECT '张三' AS name ,'语文' AS class, 100 AS score FROM system.dual UNION ALL 
SELECT '张三' AS name ,'数学' AS class, 88 AS score FROM system.dual UNION ALL 
SELECT '李四' AS name ,'语文' AS class, 98 AS score FROM system.dual UNION ALL 
SELECT '李四' AS name ,'语文' AS class, 99 AS score FROM system.dual 

SELECT name AS name , 
max(CASE WHEN class='语文' THEN score ELSE NULL END ) AS '语文', 
max(CASE WHEN class='数学' THEN score ELSE NULL END ) AS '数学' 
FROM student 
GROUP BY name; 

评论 1
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值