HIVE HSQL 基本操作命令

创建表：

　　hive>create table tablename(id int,name string,password string);

　　创建一个名字为tablename的表，表的属性有int   id;  string   name;  string  password;

创建表时指定分隔符

　　hive> create table test1(name string,count int)row format delimited fields terminated by '/t';

加载表

　　hive> load data inpath '/user/hadoop/output7/part-r-00000' into table test1;

创建一个新表，结构与其他一样
　　hive> create table table1 like table2;

　　创建一个表table1,表结构跟table2一样;

创建分区表

　　hive> create table table1(id int,line string) partitioned by (dt string,country string);

显示表里有多少条记录(count 数大于50的有多少条记录)

　　hive>select count(*) from tablename where count>50; 

排序用法order by (查询count 数大于50并排序)

　　 select * from test2 where count > 50 order by count;

显示表中有多少分区

　　hive> show partitions table1;

显示所有表

　　hive> show tables;

显示所有与u开头的表

　　hive> show tables 'u*';

显示表的结构信息

　　hive> describe test1;

 修改表名字

　　hive> alter table table1 rename to test3;

 在原表上新添加一列

　　hive> alter table test1 add columns(new_col2 int comment 'a commment');

　　hive> alter table test1 add columns(new_col3 int);

 删除表

　　hive> drop table test3;

 从本地文件加载数据：
　　hive> LOAD DATA LOCAL INPATH '/home/hadoop/input/ncdc/micro-tab/sample.txt' OVERWRITE INTO TABLE records;

 加载分区表

　　hive> load data inpath '/user/hive/warehouse/clickstream_log/dt=2016-11-29/part-r-00000' overwrite into table clickstream_log PARTITION(dt = '2016-11-30');

 显示所有函数

　　hive> show functions;

 查看函数的用法

　　hive> describe function substr;

 查看数组、map、结构
　　hive> select col1[0],col2['b'],col3.c from complex;

查看数组、map、结构
　　hive> select col1[0],col2['b'],col3.c from complex;


 内连接：
　　hive> SELECT sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);

 查看hive为某个查询使用多少个MapReduce作业
　　hive> Explain SELECT sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);

 外连接：
　　hive> SELECT sales.*, things.* FROM sales LEFT OUTER JOIN things ON (sales.id = things.id);
　　hive> SELECT sales.*, things.* FROM sales RIGHT OUTER JOIN things ON (sales.id = things.id);
　　hive> SELECT sales.*, things.* FROM sales FULL OUTER JOIN things ON (sales.id = things.id);

 in查询：Hive不支持，但可以使用LEFT SEMI JOIN
　　hive> SELECT * FROM things LEFT SEMI JOIN sales ON (sales.id = things.id);


 Map连接：Hive可以把较小的表放入每个Mapper的内存来执行连接操作
　　hive> SELECT /*+ MAPJOIN(things) */ sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);

 INSERT OVERWRITE TABLE ..SELECT：新表预先存在
　　hive> FROM records2
    　　> INSERT OVERWRITE TABLE stations_by_year SELECT year, COUNT(DISTINCT station) GROUP BY year 
    　　> INSERT OVERWRITE TABLE records_by_year SELECT year, COUNT(1) GROUP BY year
    　　> INSERT OVERWRITE TABLE good_records_by_year SELECT year, COUNT(1) WHERE temperature != 9999 AND (quality = 0 OR quality = 1 OR quality = 4 OR quality = 5 OR quality = 9) GROUP BY year;  

 CREATE TABLE ... AS SELECT：新表表预先不存在
　　hive>CREATE TABLE target AS SELECT col1,col2 FROM source;

 创建视图：
　　hive> CREATE VIEW valid_records AS SELECT * FROM records2 WHERE temperature !=9999;

 查看视图详细信息：
　　hive> DESCRIBE EXTENDED valid_records;

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传统数据库：
添加：

insert into 表名 values(); 
修改：

update 表名 set a=b where b=c; 
删除：

delete from 表名where a=b;
查询：

select * from 表名 where a=b;