Question

我有一个包含6个字段的表，如下所示：

Field1 Field2 Field3 Field4 Field5 Field6
ABC    45     XYZ           JKL    BNM
       65            QWE    JKL    
WER           YUI    IOP    GHJ

我想将上表中的数据拉到一个包含5个字段的新表中，我们忽略空值。我的决赛桌应该是这样的：

Result1 Result2 Result3 Result4 Result5
ABC     45      XYZ     JKL     BNM
65      QWE     JKL
WER     YUI     IOP     GHJ

我已经开始用CASE WHEN编写一个大规模的条件查询，但它已经失控并且容易出错。是否可以在Hive中使用regex_extract查询获取该表？

Answer 1

假设＆＃34;空值＆＃34;是空的

select  fields[0]   as Field1
       ,fields[1]   as Field2
       ,fields[2]   as Field3
       ,fields[3]   as Field4
       ,fields[4]   as Field5

from   (select  split(concat_ws(string(unhex(1)),*),'\\x01') as fields
        from    mytable
        ) t

+--------+--------+--------+--------+--------+
| field1 | field2 | field3 | field4 | field5 |
+--------+--------+--------+--------+--------+
| ABC    | 45     | XYZ    | JKL    | BNM    |
| 65     | QWE    | JKL    | (null) | (null) |
| WER    | YUI    | IOP    | GHJ    | (null) |
+--------+--------+--------+--------+--------+

简化版，假设逗号（,）未出现在您的字段中：

select  ...

from   (select  split(concat_ws(',',*),',') as fields
        from    mytable
        ) t

假设＆＃34;空值＆＃34;是空字符串

select  fields[0]   as Field1
       ,fields[1]   as Field2
       ,fields[2]   as Field3
       ,fields[3]   as Field4
       ,fields[4]   as Field5

from   (select  split(regexp_replace(concat_ws(string(unhex(1)),*),'^\\x01+|\\x01+$|(\\x01)+','$1'),'\\x01') as fields
        from    mytable
        ) t

+--------+--------+--------+--------+--------+
| field1 | field2 | field3 | field4 | field5 |
+--------+--------+--------+--------+--------+
| ABC    | 45     | XYZ    | JKL    | BNM    |
| 65     | QWE    | JKL    | (null) | (null) |
| WER    | YUI    | IOP    | GHJ    | (null) |
+--------+--------+--------+--------+--------+

简化版，假设逗号（,）未出现在您的字段中：

select  ...

from   (select  split(regexp_replace(concat_ws(',',*),'^,+|,+$|(,)+','$1'),',') as fields
        from    mytable
        ) t

在配置单元中选择下一个非空字段

1 个答案: