Google Big Query中的第三个子字符串

Question

我使用标准的sql并希望从结尾提取第三个子字符串。

Example Input: "Search-site-variable-brand-0-city-none-18053517" 
Output: "city" 

Answer 1

我只想指出，如果您打算将此转换应用于多列，将逻辑拉入UDF可能会很有用。下面是如何做到这一点的例子：

CREATE TEMP FUNCTION SecondSubstringFromEnd(s STRING) AS ((
    SELECT arr[SAFE_OFFSET(ARRAY_LENGTH(arr) - 3)] 
    FROM (
    SELECT SPLIT(s, '-') AS arr 
) 
)); 

WITH Input AS (
    SELECT 'Search-site-variable-brand-0-city-none-18053517' AS str UNION ALL 
    SELECT 'a-b' UNION ALL 
    SELECT 'w-x-yyy-z' 
) 
SELECT 
    str, 
    SecondSubstringFromEnd(str) AS second_substring_from_end 
FROM Input; 

Answer 2

这可能做的伎俩：

WITH data AS(
    select "Search-site-variable-brand-0-city-none-18053517" as Input 
) 

SELECT 
    CASE WHEN ARRAY_LENGTH(SPLIT(Input, '-')) > 3 THEN SPLIT(Input, '-')[OFFSET(ARRAY_LENGTH(SPLIT(Input, '-')) - 3)] END word 
FROM data 

它返回NULL的情况下，字符串没有裂开，如空字符串。

Answer 3

很少有更多的变化对BigQuery的标准SQL：

#standardSQL 
WITH YourTable AS(
    SELECT 'Search-site-variable-brand-0-city-none-18053517' AS Input UNION ALL 
    SELECT 'Second-substring-from-the-end-in-Google-BigQuery' UNION ALL 
    SELECT 'bigQuery-assign-a-value-to-table-1-based-on-table-2' UNION ALL 
    SELECT 'Error-Message-Too-many-sources-provided-15285-Limit-is-10000' UNION ALL 
    SELECT 'Google-Bigquery-data-import-from-Google-Analytics-360' UNION ALL 
    SELECT 'Bigquery-Partitioning-data-past-2000-limit' 
) 
SELECT 
    Input, 
    REVERSE(SPLIT(REVERSE(Input), '-')[SAFE_ORDINAL(3)]) AS Output_1, 
    ARRAY_REVERSE(SPLIT(Input, '-'))[SAFE_ORDINAL(3)] AS Output_2 
FROM YourTable