大数据学习——hive的sql练习

1新建一个数据库

 create database db3;

2创建一个外部表

--外部表建表语句示例：
create external table student_ext(Sno int,Sname string,Sex string,Sage int,Sdept string)
row format delimited 
fields terminated by ','
location '/stu';

3添加数据

vi student.txt

95001,李勇,男,20,CS
95002,刘晨,女,19,IS
95003,王敏,女,22,MA
95004,张立,男,19,IS
95005,刘刚,男,18,MA
95006,孙庆,男,23,CS
95007,易思玲,女,19,MA
95008,李娜,女,18,CS
95009,梦圆圆,女,18,MA
95010,孔小涛,男,19,CS
95011,包小柏,男,18,MA
95012,孙花,女,20,CS
95013,冯伟,男,21,CS
95014,王小丽,女,19,CS
95015,王君,男,18,MA
95016,钱国,男,21,MA
95017,王风娟,女,18,IS
95018,王一,女,19,IS
95019,邢小丽,女,19,IS
95020,赵钱,男,21,IS
95021,周二,男,17,MA
95022,郑明,男,20,MA

hdfs dfs -put student.txt /stu;

4 查询

select * from student_ext where Sno=95022;

5 group by分组

 select sex,count(1) from student_ext group by sex;

6 cluster by 分区，排序

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set mapred.reduce.tasks=4; 

select * from student_ext cluster by sno;

 create table tt_1 as select * from student_ext cluster by sno;

7