Hive命令匯總

一.啟動
1.啟動hadoop
2.直接在命令行下輸入hive就可以換啟動hive

二.創建
1.創建普通表（注意各種分隔符的寫法）

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.創建分區表（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中加載數據,指定了不存在的分區就相當於創建分區

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

三.分區表
1向分區表中添加分區

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

2刪除分區

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

四.查看信息
1查看一個分區表的分區

show partitions employees_partition;

2查看分區表的詳細信息

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刪除列（其實是重新指定列，如果沒有某列，那么就刪除了）

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創建桶表

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

2向桶表中插入數據（不能從文件中直接load）

insert into employees_bucket select * from employees_temp;

八.裝載數據
1從文件中裝載數據

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

2通過查詢語句裝載數據

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

九.查詢語句
1查詢集合中的元素
查詢數組中的元素：

select name,subordinates[0] from employees_partition;

查詢map中的元素：

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

查詢struct中的元素：

select name,address.city from employees_partition;

2在查詢中摻入計算

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

3聚合查詢(每個查詢都是針對某一列進行聚合查詢)

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

4在分區表的某個分區內查詢

select * from [table] where [分區字段名] = 'xxx'

十.視圖
1創建視圖（使用視圖限制查詢表的一部分）（創建過后是可以在show tables中查到shorter_view的）

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

2創建視圖（將表中的map等集合元素單獨列成一個表）

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

十一.其他
  1列出查詢計划

explain select sum(age) from employees_temp;

  2顯示所有函數

show functions

 3 顯示函數幫助

describe function split;