使用 bigquery 将字符串拆分为多列

Question

我在 BigQuery 中有一个包含数百万行的表，我想将 adx_catg_id 列拆分为多个新列。请注意，adx_catg_id 列包含由空格分隔的任意数量的单词。

如果字符串仅包含少于五个单词，则下面的查询示例可以将 adx_catg_id 拆分为多列。我可以扩展它以支持更多的单词，但我需要自动化它。

SELECT
  TS, str0, str2, str4, str6, str7
  from
  (select REGEXP_EXTRACT(str5, r'^(.*) .*') as str7
  from
  (select SUBSTR (str5, LENGTH(REGEXP_EXTRACT(str5, r'^(.*) .*')) + 2, LENGTH(str5)) as str6
  from
  (select REGEXP_EXTRACT(str3, r'^(.*) .*') as str5
  from
  (select SUBSTR (str3, LENGTH(REGEXP_EXTRACT(str3, r'^(.*) .*')) + 2, LENGTH(str3)) as str4
  from
  (select REGEXP_EXTRACT(str1, r'^(.*) .*') as str3
  from
  (select SUBSTR (str1, LENGTH(REGEXP_EXTRACT(str1, r'^(.*) .*')) + 2, LENGTH(str1)) as str2
  from
  (select REGEXP_EXTRACT(TS, r'^(.*) .*') as str1
  from
  (select SUBSTR(TS, LENGTH(REGEXP_EXTRACT(TS, r'^(.*) .*')) + 2,LENGTH(TS)) as str0
  from 
  (select adx_catg_id TS from [mydataset.conversions])
  ))))))))

如何循环上述查询以根据字符串长度生成新列中的所有单词？

Answer 1

看一下这个...

SELECT  
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){0}([^\s]*)\s?') as Word0,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){1}([^\s]*)\s?') as Word1,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){2}([^\s]*)\s?') as Word2,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){3}([^\s]*)\s?') as Word3,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){4}([^\s]*)\s?') as Word4,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){5}([^\s]*)\s?') as Word5,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){6}([^\s]*)\s?') as Word6, 
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){7}([^\s]*)\s?') as Word7,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){8}([^\s]*)\s?') as Word8,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){9}([^\s]*)\s?') as Word9,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){10}([^\s]*)\s?') as Word10,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){11}([^\s]*)\s?') as Word11,
Regexp_extract(StringToParse,r'^(?:[^\s]*\s){12}([^\s]*)\s?') as Word12,
FROM
(SELECT 'arbitrary number of words separated by space.' as StringToParse)

或者，如果您想要以相反的顺序：

SELECT  
Regexp_extract(StringToParse,r'\s?([^\s]*)(?:[^\s]*\s?){1}$') as Word1,
Regexp_extract(StringToParse,r'\s?([^\s]*)(?:[^\s]*\s?){2}$') as Word2,
Regexp_extract(StringToParse,r'\s?([^\s]*)(?:[^\s]*\s?){3}$') as Word3,
Regexp_extract(StringToParse,r'\s?([^\s]*)(?:[^\s]*\s?){4}$') as Word4,
Regexp_extract(StringToParse,r'\s?([^\s]*)(?:[^\s]*\s?){5}$') as Word5,
Regexp_extract(StringToParse,r'\s?([^\s]*)(?:[^\s]*\s?){6}$') as Word6, 
Regexp_extract(StringToParse,r'\s?([^\s]*)(?:[^\s]*\s?){7}$') as Word7,
FROM
(SELECT 'arbitrary number of words separated by space.' as StringToParse)

它仍然是固定数量的字段，但编码更简单且更具可读性。

希望这可以帮助