Hive 5、Hive 的数据类型 和 DDL Data Definition Language)

官方帮助文档：https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL

Hive的数据类型

-- 扩展数据类型
data_type
  : primitive_type
  | array_type
  | map_type
  | struct_type
  | union_type  -- (Note: Available in Hive 0.7.0 and later)

array_type : ARRAY < data_type >
map_type : MAP < primitive_type, data_type >
struct_type : STRUCT < col_name : data_type [COMMENT col_comment], ...>
union_type : UNIONTYPE < data_type, data_type, ... >  -- (Note: Available in Hive 0.7.0 and later)

-- 基本数据类型
primitive_type
  : TINYINT
  | SMALLINT
  | INT
  | BIGINT
  | BOOLEAN
  | FLOAT
  | DOUBLE
  | STRING
  | BINARY      -- (Note: Available in Hive 0.8.0 and later)
  | TIMESTAMP   -- (Note: Available in Hive 0.8.0 and later)
  | DECIMAL     -- (Note: Available in Hive 0.11.0 and later)
  | DECIMAL(precision, scale)  -- (Note: Available in Hive 0.13.0 and later)
  | DATE        -- (Note: Available in Hive 0.12.0 and later)
  | VARCHAR     -- (Note: Available in Hive 0.12.0 and later)
  | CHAR        -- (Note: Available in Hive 0.13.0 and later)

Hive  DDL

　　Hive完整的DDL

　　Hive DDL的语方法为类SQL语法，所以标准的SQL语法大多数在Hive中都可用；

CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name    -- (Note: TEMPORARY available in Hive 0.14.0 and later)
  [(col_name data_type [COMMENT col_comment], ...)]
  [COMMENT table_comment]
  [PARTITIONED BY (col_name data_type [COMMENT col_comment], ...)]
  [CLUSTERED BY (col_name, col_name, ...) [SORTED BY (col_name [ASC|DESC], ...)] INTO num_buckets BUCKETS]
  [SKEWED BY (col_name, col_name, ...)                  -- (Note: Available in Hive 0.10.0 and later)]
     ON ((col_value, col_value, ...), (col_value, col_value, ...), ...)
     [STORED AS DIRECTORIES]
  [
   [ROW FORMAT row_format]
   [STORED AS file_format]
     | STORED BY 'storage.handler.class.name' [WITH SERDEPROPERTIES (...)]  -- (Note: Available in Hive 0.6.0 and later)
  ]
  [LOCATION hdfs_path]
  [TBLPROPERTIES (property_name=property_value, ...)]   -- (Note: Available in Hive 0.6.0 and later)
  [AS select_statement];   -- (Note: Available in Hive 0.5.0 and later; not supported for external tables)

　　 Hive建表

-- Hive建表 语法
CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name
LIKE existing_table_or_view_name
[LOCATION hdfs_path];

create table person(
id int,
name string,
age int,
likes array<string>,
address map<string,string>
) 
row format delimited  
-- 指定导入数据的列与列之间的分隔符
fields terminated by ','  
-- 指定Array类型的分隔符
collection ITEMS TERMINATED BY  '-'
-- 指定map类型的分隔符
map keys terminated by ':'
-- 指定行与行之间的分隔符
lines terminated by '\n'; 

　　表新建成功以后可以使用desc查询表结构

　　Hive导入数据

# 三条数据，列与列之间用,号隔开；array之间用-号隔开；map之间用：号隔开；行与行用换行符隔开
1,tom,28,game-music-book,stu:henan-home:henan-work:beijing
2,jack,21,money-meinv,stu:wuhan-home:wuhan
3,lusi,18,shopping-music,stu:shanghai-home:beijing

　　导入数据：

hive> load data local inpath '/opt/data.txt' overwrite into table person;

　　

　　数据查询 

-- 查询所有
select * from person;

-- 还可以这样查
 select * from person where name='tom';

-- 或者这样
select * from person where likes[]='music';

-- 还有这样
select * from person where address['stu']='shanghai'; 

-- 还有这样
select avg(age) from person;

-- ... 等标准的SQL语法大多都可以在Hive中使用包括一些函数，因为Hive是类SQL的；

　　但在Hive中不推荐进行这些操作：Insert、Update、Delete等操作，因为Hive的特性是对数据仓库的数据进行提取，针对的数据是批量的，不适合行级的运算；

　　

　　清空表

-- 使truncate清空表
TRUNCATE TABLE person;
-- 通过覆盖的方式清空表
insert overwrite table person select * from person where 1=2;

　　删除表

drop table person;