Question

我想知道我是否可以在BigQuery中使用正则表达式从字符串中提取所有数字。

我认为下面有效但只返回第一击 - 是否有提取所有命中的方法。

我的用例是，我基本上想从网址获取最大数字，因为这更像是我需要加入的post_id。

这是我正在谈论的一个例子：

SELECT
  mystr,
  REGEXP_EXTRACT(mystr, r'(\d+)') AS nums
FROM
  (SELECT 'this is a string with some 666 numbers 999 in it 333' AS mystr),
  (SELECT 'just one number 123 in this one ' AS mystr),
  (SELECT '99' AS mystr),
  (SELECT 'another -2 example 99' AS mystr),
  (SELECT 'another-8766 example 99' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/gallery/001' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/print-preview' AS mystr)

我得到的结果是：

[
  {
    "mystr": "this is a string with some 666 numbers 999 in it 333",
    "nums": "666"
  },
  {
    "mystr": "just one number 123 in this one ",
    "nums": "123"
  },
  {
    "mystr": "99",
    "nums": "99"
  },
  {
    "mystr": "another -2 example 99",
    "nums": "2"
  },
  {
    "mystr": "another-8766 example 99",
    "nums": "8766"
  },
  {
    "mystr": "http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999",
    "nums": "2015"
  },
  {
    "mystr": "http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/gallery/001",
    "nums": "2015"
  },
  {
    "mystr": "http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/print-preview",
    "nums": "2015"
  }
]

Answer 1

经过一番挖掘，我最终得到了这个解决方案：

SELECT
  mystr,
  GROUP_CONCAT(SPLIT(REGEXP_REPLACE(mystr, r'[^\d]+', ','))) AS nums
FROM
  (SELECT 'this is a string with some 666 numbers 999 in it 333' AS mystr),
  (SELECT 'just one number 123 in this one ' AS mystr),
  (SELECT '99' AS mystr),
  (SELECT 'another -2 example 99' AS mystr),
  (SELECT 'another-8766 example 99' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/gallery/001' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/print-preview' AS mystr)

工作原理：

我首先使用正则表达式匹配任何非数字并用逗号替换
然后使用split获取结果，废弃空结果
group_concat就是在这里展示结果

Answer 2

虽然您将越来越多地在BigQuery中使用Regex，但您会发现它的实现现在非常有限 BigQuery Regular expression functions
re2 Syntax

所以很可能很快你将不得不做类似下面的事情请注意 - 对于您当前的具体示例 - 以下代码与@Cybril提供的简单解决方案完全没有任何好处此解决方案更适合您近期的潜在需求它使用javascript UDF，从而为您提供javascript regexp实现的强大功能 BigQuery User-Defined Functions

SELECT mystr, MAX(number) as max_number FROM JS(
  // input table
  (SELECT mystr FROM
    (SELECT 'this is a string with some 666 numbers 999 in it 333' AS mystr),
    (SELECT 'just one number 123 in this one ' AS mystr),
    (SELECT '99' AS mystr),
    (SELECT 'another -2 example 99' AS mystr),
    (SELECT 'another-8766 example 99' AS mystr),
    (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999' AS mystr),
    (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/gallery/001' AS mystr),
    (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/print-preview' AS mystr)
  ) ,
  // input columns
    mystr,
  // output schema
  "[
  {name: 'mystr', type: 'string'},
  {name: 'number', type: 'string'}
  ]",
  // function
  "function(r, emit){
    var numbers = r.mystr.match(/(\d+)/g);
    for (var i=0; i < numbers.length; i++) {
      emit({
        mystr: r.mystr,
        number: numbers[i]
      });
    };  
  }"
)
GROUP BY 1

当然，您也可以在UDF中移动确定最大值的逻辑，以消除额外的分组

使用正则表达式从Google BigQuery中的字符串中提取数字

2 个答案: