substring() 在配置单元中返回空白

Question

我想从一列的字段中提取最后 10 个数字，所以我在 hive 中使用内置函数的子字符串。但是如果字段值小于定义值（orig_number 140976526012 140980434512 1740016 1740016 17250460171 我正在使用此代码。 select *,length(orig_number) as leng,substr(orig_number,-10) as subbstring from num_table sort by orig_number; 输出是：

orig_number leng subbstring 140976526012 12 0976526012 140980434512 12 140980434512 1740016 7
1740016 7
17250460171 11 725046017

Answer 1

从行尾最多检索 10 个字符

select  orig_number
       ,regexp_extract (orig_number,'.{1,10}$',0)   as orig_number_suffix 

from    num_table
;

---

+--------------+--------------------+
| orig_number  | orig_number_suffix |
+--------------+--------------------+
| 140976526012 |         0976526012 |
| 140980434512 |         0980434512 |
|      1740016 |            1740016 |
|      1740016 |            1740016 |
|  17250460171 |         7250460171 |
+--------------+--------------------+

---

https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html

---

这就是你得到空白的原因。
在我看来，substr 函数的设计很糟糕。

UDFSubstr.java

private int[] makeIndex(int pos, int len, int inputLen) {
    if ((Math.abs(pos) > inputLen)) {
      return null;
    }

...