HQL表操作

1 创建表

1.1 语法

#1. 
CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name  # 表名
[(col_name data_type  [COMMENT col_comment], ...)] # 列名
[COMMENT table_comment] #表批注
[PARTITIONED BY (col_name data_type [COMMENT col_comment], ...)] # 分区
[CLUSTERED BY (col_name, col_name, ...) [SORTED BY (col_name [ASC|DESC], ...)] INTO num_buckets BUCKETS] #分桶
[
   [ROW FORMAT row_format] 
   [STORED AS file_format]
     | STORED BY 'storage.handler.class.name' [WITH SERDEPROPERTIES (...)]
] # 指定行和文件的格式化
[LOCATION hdfs_path] # 指定表存放的路径
[TBLPROPERTIES (property_name=property_value, ...)] # 指定表属性
[AS select_statement] # 在建表的时候，以当前的查询语句的结果作为表数据
​
#2.
CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name
  LIKE existing_table_or_view_name
  [LOCATION hdfs_path]; # 创建一张新表，以原有的表或者视图作为数据

1.2 相关属性

data_type
  : primitive_type
  | array_type
  | map_type
  | struct_type
  | union_type  -- (Note: Available in Hive 0.7.0 and later)
 
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)
 
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, ...)]
 
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
 
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 ]

1.3 实例

# 创建内部表
CREATE TABLE IF NOT EXISTS `users`.`info`(
`id` int COMMENT 'user id',
`name` string COMMENT 'user name',
`age` int COMMENT 'user age'
) COMMENT 'user info'
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ',';
​
# 数据加载
LOAD DATA LOCAL INPATH '' INTO TABLE table_name;

# 创建外部表
CREATE EXTERNAL TABLE IF NOT EXISTS `users`.`info_1`(
`id` int COMMENT 'user id',
`name` string COMMENT 'user name',
`age` int COMMENT 'user age'
) COMMENT 'user info'
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
LOCATION 'hdfs_path';
​
# 数据加载
LOAD DATA LOCAL INPATH '/home/user.txt' INTO TABLE `users`.`info_1`;

# 创建临时表
CREATE TEMPORARY TABLE IF NOT EXISTS `users`.`info_2`(
`id` int COMMENT 'user id',
`name` string COMMENT 'user name',
`age` int COMMENT 'user age'
) COMMENT 'user info'
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ',';
​
# 数据加载
LOAD DATA LOCAL INPATH '/home/user.txt' INTO TABLE `users`.`info_2`;

总结：

1. 当我们删除了内部表时，元数据和数据都会被删除

2. 当我们删除了外部表时，元数据会删除，数据不会被删除

3. 临时表没有元数据，而且数据也没有存放到HDFS中，他的数据都在内存里面

4. 当Hive关闭后，临时表会消失

2 修改表

2.1 语法

1. 重命名表
ALTER TABLE table_name RENAME TO new_table_name;
​
2. Alter Table Properties
ALTER TABLE table_name SET TBLPROPERTIES table_properties;
table_properties：
(property_name = property_value, property_name = property_value, ... )
​
2.1 修改表的批注信息
ALTER TABLE table_name SET TBLPROPERTIES ('comment' = new_comment);

3 修改列

3.1 语法

# 1. 修改列信息
ALTER TABLE table_name CHANGE [COLUMN] col_old_name col_new_name column_type
  [COMMENT col_comment] [FIRST|AFTER column_name] [CASCADE];
​
# 2. 添加或者删除列字段
ALTER TABLE table_name ADD|REPLACE COLUMNS (col_name data_type [COMMENT col_comment], ...)
  [CASCADE]  

3.2 实例

# 1. 修改列名
ALTER TABLE `user_1`.`t_user` CHANGE id uid int;
# 2. 修改字段类型
ALTER TABLE `user_1`.`t_user` CHANGE uid uid string;
# 2. 向表中添加字段
ALTER TABLE `user_1`.`t_user` ADD COLUMNS (birth string);
# 3. 删除列字段(birth)
ALTER TABLE `user_1`.`t_user` REPLACE COLUMNS (uid string,name string);

4 添加数据

4.1 语法

# 1. load
LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)]
​
# 2. insert
INSERT OVERWRITE TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...) [IF NOT EXISTS]] 
select_statement1 FROM from_statement;
INSERT INTO TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...)] select_statement1 FROM from_statement;

4.2 实例

# 1. load
LOAD DATA LOCAL INPATH '/home/user.txt' INTO TABLE `hive`.`t_1`;
LOAD DATA INPATH '/user.txt' INTO TABLE `hive`.`t_1`;
​
# 2. insert
CREATE TABLE `hive`.`t_user4` LIKE `hive`.`t_user3`;
INSERT OVERWRITE TABLE `hive`.`t_user4` IF NOT EXISTS
SELECT * FROM `hive`.`t_user3`;

1. local是从本地文件系统中复制数据到表目录下

2. 不加local是从HDFS文件系统中剪切数据到表目录下

3. load方式加载数据只能用于表是textfile格式的情况

5 多数据插入

5.1 语法

FROM from_statement
INSERT OVERWRITE TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...) [IF NOT EXISTS]] select_statement1
[INSERT OVERWRITE TABLE tablename2 [PARTITION ... [IF NOT EXISTS]] select_statement2]
[INSERT INTO TABLE tablename2 [PARTITION ...] select_statement2] ...;

5.2 实例

CREATE TABLE `hive`.`t_user5` LIKE `hive`.`t_user3`;
CREATE TABLE `hive`.`t_user6` LIKE `hive`.`t_user3`;
​
FROM `hive`.`t_user3`
INSERT OVERWRITE TABLE `hive`.`t_user5` IF NOT EXISTS SELECT * 
INSERT OVERWRITE TABLE `hive`.`t_user6` IF NOT EXISTS SELECT * 
;

6 Write Data

6.1 语法

INSERT OVERWRITE [LOCAL] DIRECTORY directory1
  [ROW FORMAT row_format] [STORED AS file_format] 
  SELECT ... FROM ...

6.2 实例

INSERT OVERWRITE DIRECTORY '/write'
ROW FORMAT DELIMITED
SELECT * FROM `hive`.`t_user5`;