注意 ：|，； 是特殊符號，要用 "\\|", "\\;"來表示。
一行轉多行
usertags 里面有很多項，每項之間以逗號分隔
create table tag_count2 as
select tag,count(gid) from (
select gid,tag from (select b.gid ,b.usertags from zhangb.gid_tags b group by b.gid,b.usertags) a
lateral view explode(split(a.usertags, ',')) t as tag
) p where substr(p.gid,1,7)='ANDROID' group by p.tag;
# 其中的 t 是把a表中的usertags 由一行變成多行后形成的新表的別稱，是表的名稱
導出數據：
insert overwrite local directory '/home/zhangb/tag_count'row format delimited fields terminated by '\t'
select distinct * from zhangb.tag_count
原格式：
gid1 abc,abd,abf
gid2 abc,snm
...
處理后輸出格式：
gid1 abc
gid1 abd
gid1 abf
gid2 abc
gid2 snm
...
***多行轉一行
1、演示多列轉為單行
數據文件及內容： student.txt
xiaoming|english|92.0
xiaoming|chinese|98.0
xiaoming|math|89.5
huahua|chinese|80.0
huahua|math|89.5
創建表studnet：
create table student(name string,subject string,score decimal(4,1))
row format delimited
fields terminated by '|';
導入數據：
load data local inpath '/home/hadoop/hivetestdata/student.txt' into table student;
列轉為行演示：
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
數據文件及內容： student.txt
xiaoming|english|92.0
xiaoming|chinese|98.0
xiaoming|math|89.5
huahua|chinese|80.0
huahua|math|89.5
創建表studnet：
create table student(name string,subject string,score decimal(4,1))
row format delimited
fields terminated by '|';
導入數據：
load data local inpath '/home/hadoop/hivetestdata/student.txt' into table student;
列轉為行演示：
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