Hive命令汇总

一.启动
1.启动hadoop
2.直接在命令行下输入hive就可以换启动hive

二.创建
1.创建普通表（注意各种分隔符的写法）

create table employees( name string, salary float, subordiantes array<string>, deductions map<string,float>, address struct<street:string,city:string,state:string,zip:int>) row format delimited fields terminated by ' ' collection items terminated by ',' map keys terminated by ':' lines terminated by '\n';

2.创建分区表（注意partitioned by (country string,state string)的位置）

create table employees_partition( name string, salary float, subordiantes array<string>, deductions map<string,float>, address struct<street:string,city:string,state:string,zip:int>) partitioned by (country string,state string) row format delimited fields terminated by ' ' collection items terminated by ',' map keys terminated by ':' lines terminated by '\n';

3.向hive中加载数据,指定了不存在的分区就相当于创建分区

load data local inpath '[本地文件路径]'
into table employees_partition partition (country='China',state='Liaoning');

三.分区表
1向分区表中添加分区

alter table employees_partition add [if not exists] partition(country='usa',state='ca');

2删除分区

alter table employees_partition drop [if exists] partition(country='usa',state='ca');

四.查看信息
1查看一个分区表的分区

show partitions employees_partition;

2查看分区表的详细信息

describe formatted  employees_partition;

五.重命名表

alter table employees_partition rename to employees_par;

六.修改列
1增加列

alter table employees_partition add columns(app_name string,session_id int);

2删除列（其实是重新指定列，如果没有某列，那么就删除了）

alter table employees_partition replace columns(name string,salary float,subordinates array<string>,deductions map<string,float>,address struct<street:string,city:string,state:string,zip:int>);

七.桶表
1创建桶表

create table employees_bucket(id int,name string,age int) clustered by(id) into 3 buckets row format delimited fields terminated by ',';

2向桶表中插入数据（不能从文件中直接load）

insert into employees_bucket select * from employees_temp;

八.装载数据
1从文件中装载数据

load data local inpath '[本地文件路径]' [overwrite] 
into table employees_temp [partition (country='china',state='ca')];

2通过查询语句装载数据

insert into employees_bucket [partition (country='us',state='ca')] 
select * from employees_temp;

九.查询语句
1查询集合中的元素
查询数组中的元素：

select name,subordinates[0] from employees_partition;

查询map中的元素：

select name,deductions["a"] from employees_partition;

查询struct中的元素：

select name,address.city from employees_partition;

2在查询中掺入计算

select upper(name),salary,deductions["a"],round(salary*(1-deductions["a"])) from employees_partition;

3聚合查询(每个查询都是针对某一列进行聚合查询)

select count(*),avg(salary) from employees_partition;

4在分区表的某个分区内查询

select * from [table] where [分区字段名] = 'xxx'

十.视图
1创建视图（使用视图限制查询表的一部分）（创建过后是可以在show tables中查到shorter_view的）

create view shorter_view as
    > select * from employees_temp > where id > 2;

2创建视图（将表中的map等集合元素单独列成一个表）

create view shorter_view2(street,city,state) as
    > select deductions["a"],deductions["b"],deductions["c"]
    > from employees_partition;

十一.其他
  1列出查询计划

explain select sum(age) from employees_temp;

  2显示所有函数

show functions

 3 显示函数帮助

describe function split;