hive复杂数据类型

目录

1.arrays

2.map

3.struct

1.arrays

创建一个表，指定一个location字段的数据类型为array

hive> create table  person
(name string, 
work_locations array )
ROW FORMAT DELIMITED 
FIELDS TERMINATED BY 't'
COLLECTION ITEMS TERMINATED BY ',';

 注意我在文本中录入数据的使用制表符分割，然后将数据加载到表中

hive> select * from person;
OK
a	["beijing","shanghai","tianjin","hangzhou"]
b	["beijing","shanghai","tianjin","hangzhou"]

上面建表的时候较多了一个collection items terminated,是指定集合里面的内容用什么分割，上面还有一个字段分割，这两分割字段是不能重复的，重复的话那就认定都是前面的字段，后一个字段的内容就都是null

 

既然是数组，就可以读取数组里面的元素

hive> select name,work_locations[0] from person;
OK
a	beijing
b	beijing

如果是越界的下标不会报错，只是返回null 

hive> select work_locations[4] from person where name='a' ;
OK
NULL

2.map

建表语句

create table scoremap(name string, score map )
ROW FORMAT DELIMITED
FIELDS TERMINATED BY 't'
COLLECTION ITEMS TERMINATED BY ','
MAP KEYS TERMINATED BY ':';

将数据导入表中 

查询所有数据

hive> select * from scoremap;
OK
小明	{"数学":80,"语文":89,"英语":95}
小红	{"语文":60,"数学":80,"英语":99}

 查询map中的value值;

hive> select score['数学'] from scoremap;
OK
80
80

3.struct

create table scoreStruct(
    name string,
    score struct 
)ROW FORMAT DELIMITED
FIELDS TERMINATED BY 't'
COLLECTION ITEMS TERMINATED BY ',';

需要导入的数据 

小明	语文,91,000001,余老师
小红	数学,100,000002,体育老师

hive> select * from scoreStruct;
OK
小明	{"course":"语文","score":91,"course_id":1,"tearcher":"余老师"}
小红	{"course":"数学","score":100,"course_id":2,"tearcher":"体育老师"}