Question

我有150,000行数据，我试图在Google BigQuery中查询。

列Text包含不同长度的文本，我想从中查询特定关键字。

我已经知道下面的查询返回包含特定关键字的所有行（例如facebook）：

SELECT Text From Data.Set_1 
WHERE Text CONTAINS 'facebook'

问题：

1）如何改进查询，以便返回关键字＆＃39; facebook＆＃39;的所有匹配项的总计数。跨越＆＃39; Text＆＃39;在一个新专栏？

2）如何将其升级为多个关键词（facebook，cnn，bbc，twitter）并返回数据中存在的每个关键词的总数（例如facebook 42，cnn 54，bbc 88，twitter 49）？< / p>

Answer 1

您可以使用派生表来包含您要查找的所有单词，然后使用聚合来计算匹配项：

SELECT w.keyword, COUNT(s.Text)
From (SELECT 'facebook' as keyword UNION ALL
      SELECT 'cnn'
     ) w LEFT JOIN
     Data.Set_1 s
     ON s.Text CONTAINS w.keyword
GROUP BY w.keyword;

请注意：这不是特别有效。性能应该与关键字数量大致呈线性关系。

Answer 2

for BigQuery Legacy SQL

SELECT 
  keyword, 
  COUNT(1) AS rows, 
  SUM(INTEGER((LENGTH(Text) - LENGTH(REPLACE(Text, keyword, ''))) / LENGTH(keyword))) AS occurences 
FROM YourTable 
CROSS JOIN keywords
WHERE Text CONTAINS keyword
GROUP BY keyword

使用

的示例

SELECT 
  keyword, 
  COUNT(1) AS rows, 
  SUM(INTEGER((LENGTH(Text) - LENGTH(REPLACE(Text, keyword, ''))) / LENGTH(keyword))) AS occurences 
FROM (
  SELECT Text FROM
    (SELECT 'facebookfacebookcnnbbccnn' AS Text),
    (SELECT 'facebook' AS Text), 
    (SELECT 'cnn' AS Text)
) AS words 
CROSS JOIN (
  SELECT keyword FROM 
    (SELECT 'facebook' AS keyword),
    (SELECT 'cnn' AS keyword), 
    (SELECT 'bbc' AS keyword)
) AS keywords
WHERE Text CONTAINS keyword
GROUP BY keyword

对于BigQuery Standard SQL（请参阅Enabling Standard SQL）

SELECT 
  keyword, 
  COUNT(1) AS `rows`, 
  SUM((LENGTH(Text) - LENGTH(REPLACE(Text, keyword, ''))) / LENGTH(keyword)) AS occurences  
FROM YourTable 
JOIN keywords
ON STRPOS(Text, keyword) > 0
GROUP BY keyword

使用

的示例

WITH keywords AS (
  SELECT 'facebook' AS keyword UNION ALL
  SELECT 'cnn' AS keyword UNION ALL
  SELECT 'bbc' AS keyword 
),
words AS (
  SELECT 'facebookfacebookcnnbbccnn' AS Text UNION ALL
  SELECT 'facebook' AS Text UNION ALL
  SELECT 'cnn' AS Text 
)
SELECT 
  keyword, 
  COUNT(1) AS `rows`, 
  SUM((LENGTH(Text) - LENGTH(REPLACE(Text, keyword, ''))) / LENGTH(keyword)) AS occurences  
FROM words 
JOIN keywords
ON STRPOS(Text, keyword) > 0
GROUP BY keyword

如何搜索包含特定单词的行，然后返回每个单词的计数？

2 个答案: