大数据之Hive：space函数

Posted 2022-03-01 浊酒南街

目录

• 1、空格字符串函数：space
• 2、space函数与split函数结合，得到数组；
• 3、如何产生1-100的连续的数字？

1、空格字符串函数：space

语法: space(int n)
返回值: string
说明：返回长度为n的空格字符串
举例：

hive> select space(10) from dual;
hive> select length(space(10)) from dual;
10

2、space函数与split函数结合，得到数组；

space函数与split函数结合，可以得到空格字符串数组
举例：

hive>select split(space(10), '');
[" "," "," "," "," "," "," "," "," "," ",""]

3、如何产生1-100的连续的数字？

结合space函数与split函数，posexplode函数，lateral view函数获得
实现方法一：

select
id_start+pos as id
from(
    select
    1 as id_start,
    100 as id_end
) m  lateral view posexplode(split(space(id_end-id_start), '')) t as pos, val

实现方法二：

select
  row_number() over() as id
from  
  (select split(space(99), ' ') as x) t
lateral view
explode(x) ex;

备注：explode(x)和posexplode(）均为炸裂函数，区别在于explode炸出一个值，posexplode不仅炸出一个值还附带索引号；