1.复杂类型
这小节演示下Hive的复杂类型，也就是Array、Map和Struct
那我们先来一份数据，
cat data.txt
1001 zhangsan a1,b1,c1 a1:88,b1:39,c1:98 bj,[email protected],18210111011
1002 lisi a2,b2,c2 a2:99,b2:23,c2:81 tj,ls@123,com,13611211121有了数据我们开始建表并导入数据
-- 建表
create table demo_t1(
id int,
name string,
courses array,
score map,
info struct)
row format delimited fields terminated by "\t"
collection items terminated by ","
map keys terminated by":"
lines terminated by "\n";
-- 导入数据
load data local inpath "/home/v2admin/demo/array_demo/data.txt" into table demo_t1; 查询下 select * from demo_t1;
+-------------+---------------+-------------------+----------------------------+----------------------------------------------------+
| demo_t1.id | demo_t1.name | demo_t1.courses | demo_t1.score | demo_t1.info |
+-------------+---------------+-------------------+----------------------------+----------------------------------------------------+
| 1001 | zhangsan | ["a1","b1","c1"] | {"a1":88,"b1":39,"c1":98} | {"address":"bj","email":"[email protected]","phone":"18210111011"} |
| 1002 | lisi | ["a2","b2","c2"] | {"a2":99,"b2":23,"c2":81} | {"address":"tj","email":"ls@123","phone":"com"} |
+-------------+---------------+-------------------+----------------------------+----------------------------------------------------+
- Array
我们查看下每个人的课程
select name,courses from demo_t1;
+-----------+-------------------+
| name | courses |
+-----------+-------------------+
| zhangsan | ["a1","b1","c1"] |
| lisi | ["a2","b2","c2"] |
+-----------+-------------------+我们只看第一个课程
select name,courses[0] from demo_t1;
+-----------+------+
| name | _c1 |
+-----------+------+
| zhangsan | a1 |
| lisi | a2 |
+-----------+------+- map
我们查看下每个人的score
select name,score from demo_t1;
+-----------+----------------------------+
| name | score |
+-----------+----------------------------+
| zhangsan | {"a1":88,"b1":39,"c1":98} |
| lisi | {"a2":99,"b2":23,"c2":81} |
+-----------+----------------------------+我们只看a1课程的成绩
select name,score['a1'] from demo_t1;
+-----------+-------+
| name | _c1 |
+-----------+-------+
| zhangsan | 88 |
| lisi | NULL |
+-----------+-------+
- struct
我们看下每个人的info
select name,info from demo_t1;
+-----------+----------------------------------------------------+
| name | info |
+-----------+----------------------------------------------------+
| zhangsan | {"address":"bj","email":"[email protected]","phone":"18210111011"} |
| lisi | {"address":"tj","email":"ls@123","phone":"com"} |
+-----------+----------------------------------------------------+我们查看下每个人的地址
select name,info.address from demo_t1;
+-----------+----------+
| name | address |
+-----------+----------+
| zhangsan | bj |
| lisi | tj |
+-----------+----------+2 视图
Hive视图跟mysql等关系型数据库的视图类似，有以下特点
1）Hive中的视图是逻辑层面的
2）Hive中的视图只能提供查询功能，不能进行增删改查的操作
3）Hive中的视图在创建时，保存的只是元数据，只要在真正使用视图查询时，才会执行视图对应的子查询语句。
- 创建视图
和mysql类似
create view view_demo as select id,name from demo_t1;- 使用视图
select name from view_demo;- 删除视图
drop view view_demo;