Hive中行列转换

1、演示多列转为单行

数据文件及内容： student.txt

xiaoming|english|92.0

xiaoming|chinese|98.0

xiaoming|math|89.5

huahua|chinese|80.0

huahua|math|89.5



创建表studnet：

create table student(name string,subject string,score decimal(4,1))

row format delimited

fields terminated by '|';



导入数据：

load data local inpath '/home/hadoop/hivetestdata/student.txt' into table student;





列转为行演示：

hive (hive)> select name,concat_ws(',',collect_set(subject)) from student group by name;

huahua    chinese,math

xiaoming english,chinese,math





hive (hive)> select name,concat_ws(',',collect_set(concat(subject,'=',score))) from student group by name;

huahua chinese=80,math=89.5

xiaoming english=92,chinese=98,math=89.5





2、演示单行转为多列

数据文件及内容：student2.txt

huahua|chinese=80,math=89.5

xiaoming|english=92,chinese=98,math=89.5



创建表：

create table student2(name string,subject_score_list string)

row format delimited

fields terminated by '|';

导入数据：

load data local inpath '/home/hadoop/hivetestdata/student2.txt' into table student2;



行转为列演示：

hive (hive)> select * from student2;

student2.name student2.subject_score_list

huahua             chinese=80,math=89.5

xiaoming          english=92,chinese=98,math=89.5





hive (hive)> select name, subject_list from student2 stu2 lateral view explode(split(stu2.subject_score_list,','))stu_subj as subject_list; ----别名一定不要忘记

huahua    chinese=80

huahua    math=89.5

xiaoming english=92

xiaoming chinese=98

xiaoming math=89.5





Impala的行列转换请查看： http://blog.csdn.net/jiangshouzhuang/article/details/46809931