HIVE基本操作

1、启动远程服务端：hive --service metastore启动（这里是阻塞式），然后在客户端操作

2、Hive DDL（数据库定义语言）

--展示所有数据库
	show databases;
--切换数据库
	use database_name;

3、创建语法（建议拷贝到notepad++中，查看类型时比较方便有高亮）

/*
	创建表的操作
		基本语法：
		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], ... [constraint_specification])]
  		[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)
 
		CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name
  			LIKE existing_table_or_view_name
  		[LOCATION hdfs_path];
 		复杂数据类型
		data_type
  		 : primitive_type
  		 | array_type
  		 | map_type
  		 | struct_type
  		 | union_type  -- (Note: Available in Hive 0.7.0 and later)
 		基本数据类型
		primitive_type
 		 : TINYINT
 		 | SMALLINT
 		 | INT
 		 | BIGINT
 		 | BOOLEAN
 		 | FLOAT
 		 | DOUBLE
  		 | DOUBLE PRECISION -- (Note: Available in Hive 2.2.0 and later)
 		 | 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)
 
		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)
 		行格式规范
		row_format
 		 : DELIMITED [FIELDS TERMINATED BY char [ESCAPED BY char]] [COLLECTION ITEMS 				TERMINATED BY char]
 	       [MAP KEYS TERMINATED BY char] [LINES TERMINATED BY char]
	       [NULL DEFINED AS char]   -- (Note: Available in Hive 0.13 and later)
  			| SERDE serde_name [WITH SERDEPROPERTIES (property_name=property_value, 				property_name=property_value, ...)]
 		文件基本类型
		file_format:
 		 : SEQUENCEFILE
 		 | TEXTFILE    -- (Default, depending on hive.default.fileformat configuration)
 		 | RCFILE      -- (Note: Available in Hive 0.6.0 and later)
 		 | ORC         -- (Note: Available in Hive 0.11.0 and later)
 		 | PARQUET     -- (Note: Available in Hive 0.13.0 and later)
 		 | AVRO        -- (Note: Available in Hive 0.14.0 and later)
 		 | JSONFILE    -- (Note: Available in Hive 4.0.0 and later)
 		 | INPUTFORMAT input_format_classname OUTPUTFORMAT output_format_classname
 		表约束
		constraint_specification:
 		 : [, PRIMARY KEY (col_name, ...) DISABLE NOVALIDATE ]
 		   [, CONSTRAINT constraint_name FOREIGN KEY (col_name, ...) REFERENCES 					table_name(col_name, ...) DISABLE NOVALIDATE 
*/

--创建普通hive表（不包含行定义格式）
	create table psn
	(
	id int,
	name string,
	likes array<string>,
	address map<string,string>
	)

--创建自定义行格式的hive表
	create table psn2
	(
	id int,
	name string,
	likes array<string>,
	address map<string,string>
	)
	row format delimited
	fields terminated by ','
	collection items terminated by '-'
	map keys terminated by ':';

--创建hive的外部表(需要添加external和location的关键字)
create external table psn4
	(
	id int,
	name string,
	likes array<string>,
	address map<string,string>
	)
	row format delimited
	fields terminated by ','
	collection items terminated by '-'
	map keys terminated by ':'
	location '/data';
/*
	在之前创建的表都属于hive的内部表（psn,psn2,psn3）,而psn4属于hive的外部表，
	内部表跟外部表的区别：
		1、hive内部表创建的时候数据存储在hive的默认存储目录中，外部表在创建的时候需要制定额外的目录
		2、hive内部表删除的时候，会将元数据和数据都删除，而外部表只会删除元数据，不会删除数据
	应用场景:
		内部表:需要先创建表，然后向表中添加数据，适合做中间表的存储
		外部表：可以先创建表，再添加数据，也可以先有数据，再创建表，本质上是将hdfs的某一个目录的数据跟				hive的表关联映射起来，因此适合原始数据的存储，不会因为误操作将数据给删除掉
*/