1 行轉列

1.1 函數

CONCAT(string A/col, string B/col…)：返回輸入字符串連接后的結果，支持任意個輸入字符串;

CONCAT_WS(separator, str1, str2,...)：它是一個特殊形式的 CONCAT()。第一個參數剩余參數間的分隔符。分隔符可以是與剩余參數一樣的字符串。如果分隔符是 NULL，返回值也將為 NULL。這個函數會跳過分隔符參數后的任何 NULL 和空字符串。分隔符將被加到被連接的字符串之間;

COLLECT_SET(col)：函數只接受基本數據類型，它的主要作用是將某字段的值進行去重匯總，產生array類型字段。?將某列數據轉換成數組

1.1.1 concat字符串的拼接

0: jdbc:hive2://linux01:10000> desc fromatted concat ;

FAILED: SemanticException [Error 10001]: Table not found fromatted

Error: Error while compiling statement: FAILED: SemanticException [Error 10001]: Table not found fromatted (state=42S02,code=10001)

0: jdbc:hive2://linux01:10000> desc formatted concat ;

FAILED: SemanticException [Error 10001]: Table not found concat

Error: Error while compiling statement: FAILED: SemanticException [Error 10001]: Table not found concat (state=42S02,code=10001)

0: jdbc:hive2://linux01:10000> desc function concat ;

OK

+----------------------------------------------------+

| tab_name |

+----------------------------------------------------+

| concat(str1, str2, ... strN) - returns the concatenation of str1, str2, ... strN or concat(bin1, bin2, ... binN) - returns the concatenation of bytes in binary data bin1, bin2, ... binN |

+----------------------------------------------------+

示例? 實現字符串的拼接

0: jdbc:hive2://linux01:10000> select concat("a" , "-->","b","-->","c")

. . . . . . . . . . . . . . .> ;

OK

+------------+

| _c0 |

+------------+

| a-->b-->c |

+------------+

concat的執行時機時行數據? 將查詢的表中的一行中的多個字段拼接

0: jdbc:hive2://linux01:10000> select concat(ename,":",job,":",sal) from tb_emp;

OK

+--------------------------+

| _c0 |

+--------------------------+

| SMITH:CLERK:800.0 |

| ALLEN:SALESMAN:1600.0 |

| WARD:SALESMAN:1250.0 |

| JONES:MANAGER:2975.0 |

| MARTIN:SALESMAN:1250.0 |

| BLAKE:MANAGER:2850.0 |

| CLARK:MANAGER:2450.0 |

| SCOTT:ANALYST:3000.0 |

| KING:PRESIDENT:5000.0 |

| TURNER:SALESMAN:1500.0 |

| ADAMS:CLERK:1100.0 |

| JAMES:CLERK:950.0 |

| FORD:ANALYST:3000.0 |

| MILLER:CLERK:1300.0 |

| HUGUANYU:HANGGE:18000.0 |

+--------------------------+

1.1.2?CONCAT_WS(separator, str1, str2,...)

concat_ws 比 concat 可以自定字段的分隔符

concat_ws (參數一(分隔符) , str1 , str2....)

concat_ws (參數一(分隔符) , 數組)

示例

0: jdbc:hive2://linux01:10000> select concat_ws("_" , "tom","cat" ,"jim" ,"jerry") ;

OK

+--------------------+

| _c0 |

+--------------------+

| tom_cat_jim_jerry |

+--------------------+

0: jdbc:hive2://linux01:10000> select concat_ws(":" , ename ,job , sal) from tb_emp ;

FAILED: SemanticException [Error 10016]: Line 1:36 Argument type mismatch 'sal': Argument 4 of function CONCAT_WS must be "string or array", but "double" was found.

Error: Error while compiling statement: FAILED: SemanticException [Error 10016]: Line 1:36 Argument type mismatch 'sal': Argument 4 of function CONCAT_WS must be "string or array", but "double" was found. (state=42000,code=10016)

需要類型轉換 將double轉換成string? 語法

cast(變量? AS 數據類型) 強制類型轉換

cast(sal as string)

select concat_ws(":" , ename ,job , cast(sal as string)) from tb_emp ;

OK

+--------------------------+

| _c0 |

+--------------------------+

| SMITH:CLERK:800.0 |

| ALLEN:SALESMAN:1600.0 |

| WARD:SALESMAN:1250.0 |

| JONES:MANAGER:2975.0 |

| MARTIN:SALESMAN:1250.0 |

| BLAKE:MANAGER:2850.0 |

| CLARK:MANAGER:2450.0 |

| SCOTT:ANALYST:3000.0 |

| KING:PRESIDENT:5000.0 |

| TURNER:SALESMAN:1500.0 |

| ADAMS:CLERK:1100.0 |

| JAMES:CLERK:950.0 |

| FORD:ANALYST:3000.0 |

| MILLER:CLERK:1300.0 |

| HUGUANYU:HANGGE:18000.0 |

+--------------------------+

1.1.3?COLLECT_SET(col) 將內容收集成set集合

desc function collect_set ;

OK

+----------------------------------------------------+

| tab_name |

+----------------------------------------------------+

| collect_set(x) - Returns a set of objects with duplicate elements eliminated |

+----------------------------------------------------+

對表中的某個字段列操作

select deptno from tb_emp ;

OK

+---------+

| deptno |

+---------+

| 20 |

| 30 |

| 30 |

| 20 |

| 30 |

| 30 |

| 10 |

| 20 |

| 10 |

| 30 |

| 20 |

| 30 |

| 20 |

| 10 |

| 50 |

+---------+

select conllect_set(deptno) from tb_emp ;--->去重重復元素的數組

+----------------+

| _c0 |

+----------------+

| [20,30,10,50] |

+----------------+

collect_list(col)? 不會去重數據

select collect_list(deptno) as deptno_list from tb_emp ;

+-------------------------------------------------+

| deptno_list |

+-------------------------------------------------+

| [20,30,30,20,30,30,10,20,10,30,20,30,20,10,50] |

+-------------------------------------------------+

1.2 行轉列

結果如下：

射手座,A ???????????娜娜|鳳姐

白羊座,A ???????????孫悟空|豬八戒

白羊座,B ???????????宋宋

數據

孫悟空? ?白羊座 A

娜娜 ?????射手座 A

宋宋 ?????白羊座 B

豬八戒????白羊座 A

鳳姐 ?????射手座 A

1.2.1 建表導入數據

create table if not exists tb_star(

name string ,

star string ,

dname string

)

row format delimited fields terminated by "\t" ;

load data local inpath "/hive/data/star.txt" into table tb_star ;

0: jdbc:hive2://linux01:10000> select * from tb_star ;

OK

+---------------+---------------+----------------+

| tb_star.name | tb_star.star | tb_star.dname |

+---------------+---------------+----------------+

| 孫悟空 | 白羊座 | A |

| 娜娜 | 射手座 | A |

| 宋宋 | 白羊座 | B |

| 豬八戒 | 白羊座 | A |

| 鳳姐 | 射手座 | A |

+---------------+---------------+----------------+

1.2.2 代碼實現方式一

1) 先將星座和部門拼接 concat_ws

select

concat_ws("," , star , dname) as star_and_dname ,

name

from

tb_star ;

+-----------------+-------+

| star_and_dname | name |

+-----------------+-------+

| 白羊座,A | 孫悟空 |

| 射手座,A | 娜娜 |

| 白羊座,B | 宋宋 |

| 白羊座,A | 豬八戒 |

| 射手座,A | 鳳姐 |

+-----------------+-------+

2) 分組 收集姓名

with t1 as

(select

concat_ws("," , star , dname) as star_and_dname ,

name

from

tb_star)

select

star_and_dname,

collect_set(name)

from

t1

group by star_and_dname ;

+-----------------+----------------+

| star_and_dname | _c1 |

+-----------------+----------------+

| 射手座,A | ["娜娜","鳳姐"] |

| 白羊座,A | ["孫悟空","豬八戒"] |

| 白羊座,B | ["宋宋"] |

+-----------------+----------------+

3) 獲取結果

select

star_and_dname ,

concat_ws("|" ,name_arr )

from

(select

star_and_dname,

collect_set(name) as name_arr

from

(select

concat_ws("," , star , dname) as star_and_dname ,

name

from

tb_star) t

group by star_and_dname) t2 ;

+-----------------+----------+

| star_and_dname | _c1 |

+-----------------+----------+

| 射手座,A | 娜娜|鳳姐 |

| 白羊座,A | 孫悟空|豬八戒 |

| 白羊座,B | 宋宋 |

+-----------------+----------+

1.2.3 代碼實現方式二

select

concat(star , "," , dname) ,

concat_ws("|" , collect_set(name))

from

tb_star

group by star , dname

;

+--------+----------+

| _c0 | _c1 |

+--------+----------+

| 射手座,A | 娜娜|鳳姐 |

| 白羊座,A | 孫悟空|豬八戒 |

| 白羊座,B | 宋宋 |

+--------+----------+

2 列轉行

2.1 關鍵函數

split(str , 分隔符)? 返回一個數組

0: jdbc:hive2://linux01:10000> select split("hello,jim,yonggge,tom,cat" , ",") ;

OK

+----------------------------------------+

| _c0 |

+----------------------------------------+

| ["hello","jim","yonggge","tom","cat"] |

+----------------------------------------+

explode()? 炸裂函數? 將數組中的每個元素顯示在每行中

0: jdbc:hive2://linux01:10000> select explode (split("hello,jim,yonggge,tom,cat" , ",")) ;

OK

+----------+

| col |

+----------+

| hello |

| jim |

| yonggge |

| tom |

| cat |

+----------+

lateral view? 側窗口函數

2.2 示例

2.2.1 數據和需求

數據

《疑犯追蹤》?? ?懸疑,動作,科幻,劇情

《Lie to me》?? ?懸疑,警匪,動作,心理,劇情

《戰狼2》?? ?戰爭,動作,災難

需求 獲取如下結構

《疑犯追蹤》 ? ? ?懸疑

《疑犯追蹤》 ? ? ?動作

《疑犯追蹤》 ? ? ?科幻

《疑犯追蹤》 ? ? ?劇情

《Lie to me》 ? 懸疑

《Lie to me》 ? 警匪

《Lie to me》 ? 動作

《Lie to me》 ? 心理

《Lie to me》 ? 劇情

《戰狼2》 ? ? ? ?戰爭

《戰狼2》 ? ? ? ?動作

《戰狼2》 ? ? ? ?災難

2.2.2 建表導入數據

create table tb_movie(

name string ,

types string

)

row format delimited fields terminated by "\t" ;

load data local inpath "/hive/data/movie.txt" into table tb_movie ;

+----------------+-----------------+

| tb_movie.name | tb_movie.types |

+----------------+-----------------+

| 《疑犯追蹤》 | 懸疑,動作,科幻,劇情 |

| 《Lie to me》 | 懸疑,警匪,動作,心理,劇情 |

| 《戰狼2》 | 戰爭,動作,災難 |

+----------------+-----------------+

2.2.3 實現

1 將類型轉換成數組

select

split(types , ",") types_arr

from

tb_movie ;

2 炸裂

select

explode(split(types , ",")) f_type

from

tb_movie ;

+---------+

| f_type |

+---------+

| 懸疑 |

| 動作 |

| 科幻 |

| 劇情 |

| 懸疑 |

| 警匪 |

| 動作 |

| 心理 |

| 劇情 |

| 戰爭 |

| 動作 |

| 災難 |

+---------+

3 使用側窗口函數拼接

select

name ,

f_type

from

tb_movie

lateral view

explode(split(types ,",")) t as f_type ;

+--------------+---------+

| name | f_type |

+--------------+---------+

| 《疑犯追蹤》 | 懸疑 |

| 《疑犯追蹤》 | 動作 |

| 《疑犯追蹤》 | 科幻 |

| 《疑犯追蹤》 | 劇情 |

| 《Lie to me》 | 懸疑 |

| 《Lie to me》 | 警匪 |

| 《Lie to me》 | 動作 |

| 《Lie to me》 | 心理 |

| 《Lie to me》 | 劇情 |

| 《戰狼2》 | 戰爭 |

| 《戰狼2》 | 動作 |

| 《戰狼2》 | 災難 |

+--------------+---------+

總結

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