1. Hive 中DDL

结构化语言查询对于所有数据库语法都大同小异的。

1) 数据库操作

# 查询数据库
show databases;
# 切换数据库
USE database_name;
USE DEFAULT;
# 创建数据库
CREATE [REMOTE] (DATABASE|SCHEMA) [IF NOT EXISTS] database_name
  [COMMENT database_comment]
  [LOCATION hdfs_path]
  [MANAGEDLOCATION hdfs_path]
  [WITH DBPROPERTIES (property_name=property_value, ...)];
create DATABASE test;
# 删除数据库
DROP (DATABASE|SCHEMA) [IF EXISTS] database_name [RESTRICT|CASCADE];
drop database test;

实操

2) 创建表 Create table

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 [column_constraint_specification] [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];
# 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)
 ## List集合 
array_type
  : ARRAY < data_type >
# map集合
map_type
  : MAP < primitive_type, data_type >
 # 结构
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，分隔符
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, ...)]
 # 文件格式
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
 # 列约束
column_constraint_specification:
  : [ PRIMARY KEY|UNIQUE|NOT NULL|DEFAULT [default_value]|CHECK  [check_expression] ENABLE|DISABLE NOVALIDATE RELY/NORELY ]
 
default_value:
  : [ LITERAL|CURRENT_USER()|CURRENT_DATE()|CURRENT_TIMESTAMP()|NULL ] 
 
constraint_specification:
  : [, PRIMARY KEY (col_name, ...) DISABLE NOVALIDATE RELY/NORELY ]
    [, PRIMARY KEY (col_name, ...) DISABLE NOVALIDATE RELY/NORELY ]
    [, CONSTRAINT constraint_name FOREIGN KEY (col_name, ...) REFERENCES table_name(col_name, ...) DISABLE NOVALIDATE 
    [, CONSTRAINT constraint_name UNIQUE (col_name, ...) DISABLE NOVALIDATE RELY/NORELY ]
    [, CONSTRAINT constraint_name CHECK [check_expression] ENABLE|DISABLE NOVALIDATE RELY/NORELY ]

实操

• 创建表从本地加载文件

CREATE TABLE person(
id INT,
name STRING,
age INT,
likes ARRAY<STRING>,
address MAP<STRING,STRING>
 )
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
COLLECTION ITEMS TERMINATED BY '-'
MAP KEYS TERMINATED BY ':'
LINES TERMINATED BY '\n';

• 准备数据文件

1,elite0,10,basketball-music-dance,adderss:xx
2,elite1,20,basketball-music-dance,adderss:xx
3,elite2,10,basketball-music-dance,adderss:xx
4,elite3,20,basketball-music-dance,adderss:xx
5,elite4,10,basketball-music-dance,adderss:xx
6,elite5,20,basketball-music-dance,adderss:xx

• 在linux下创建文件

mkdir -p /var/bigdata/hive/
cd /var/bigdata/hive/
vi data.txt

• 从文件加载数据到表

LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)]
#加载本地文件到表
load data local inpath '/var/bigdata/hive/data.txt' into table person;
# 查询加载的数据
select * from person;

3）内部外部表区别

	内部表	外部表
创建语法	CREATE TABLE [IF NOT EXISTS] table_name	CREATE EXTERNAL TABLE [IF NOT EXISTS] table_name
区别	删除表时，元数据与数据都会被删除	删除外部表只删除metastore的元数据，不删除hdfs中的表数据

4) Create Table As Select (CTAS)

4）分区表 partition

单分区建表语句：

create table day_table (id int, content string) partitioned by(col string);
# 需要注意分区表的列创建的时候字段就不需要加，加上创建会报列重复
CREATE TABLE person3(
id INT,
name STRING,
likes ARRAY<STRING>,
address MAP<STRING,STRING>
 )partitioned by(age int) 
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
COLLECTION ITEMS TERMINATED BY '-'
MAP KEYS TERMINATED BY ':'
LINES TERMINATED BY '\n';

加载文件数据的时候需要指定分区

删除分区

ALTER TABLE table_name DROP partition_spec, partition_spec,...
##删除分区
ALTER TABLE person3 DROP partition(age=20)

效果如下

ALTER TABLE person3 DROP partition(age=20);
Dropped the partition age=20
OK
Time taken: 0.831 seconds
hive> select * from person3;;
OK
1	elite0	["10"]	{"basketball":null,"music":null,"dance":null}	10
2	elite1	["20"]	{"basketball":null,"music":null,"dance":null}	10
3	elite2	["10"]	{"basketball":null,"music":null,"dance":null}	10
4	elite3	["20"]	{"basketball":null,"music":null,"dance":null}	10
5	elite4	["10"]	{"basketball":null,"music":null,"dance":null}	10
6	elite5	["20"]	{"basketball":null,"music":null,"dance":null}	10

双分区建表语句：

create table day_hour_table (id int, content string)
partitioned by (col1 string, col string);

其他的可以参考官网进行实战。

2 .Hive中 DML

1）从文件加载数据 Loading files into tables

语法：

LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)]
 
LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)] [INPUTFORMAT 'inputformat' SERDE 'serde'] (3.0 or later)

上边已经操作过，不在操作。

2）插入 INSERT

• into Hive tables from queries

• into directories from queries

• into Hive tables from SQL

3）更新 UPDATE

UPDATE tablename SET column = value [, column = value ...] [WHERE expression]

4）删除 DELETE

DELETE FROM tablename [WHERE expression]

5）合并 MERGE

MERGE INTO <target table> AS T USING <source expression/table> AS S
ON <boolean expression1>
WHEN MATCHED [AND <boolean expression2>] THEN UPDATE SET <set clause list>
WHEN MATCHED [AND <boolean expression3>] THEN DELETE
WHEN NOT MATCHED [AND <boolean expression4>] THEN INSERT VALUES<value list>