Hive基本使用_hg路hive

启动Hadoop：

${HADOOP_HOME}/sbin/start-all.sh

启动Hive：

${HIVE_HOME}/bin/hive

创建表:

CREATE  TABLE table_name
  [(col_name data_type [COMMENT col_comment])]
 
create table hive_wordcount(context string);

加载数据到hive表

LOAD DATA LOCAL INPATH 'filepath' INTO TABLE tablename 
 
load data local inpath '/home/hadoop/data/hello.txt' into table hive_wordcount;

查询：

select word, count(1) from hive_wordcount lateral view explode(split(context,'\t')) wc as word group by word;
 
lateral view explode(): 是把每行记录按照指定分隔符进行拆解

hive ql提交执行以后会生成mr作业，并在yarn上运行

删除表：

drop table hive_wordcount;

完整例子：

create table emp(
empno int,
ename string,
job string,
mgr int,
hiredate string,
sal double,
comm double,
deptno int
) ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t';
 
create table dept(
deptno int,
dname string,
location string
) ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t';
 
load data local inpath '/home/hadoop/data/emp.txt' into table emp;
load data local inpath '/home/hadoop/data/dept.txt' into table dept;
 
求每个部门的人数
select deptno, count(1) from emp group by deptno;