(SQL) 识别字段中字符串格式多次出现的位置

Question

我需要将叙述字段（自由文本）拆分为多行。目前的格式如下：

Case_Reference | Narrative
```````````````|`````````````````````````````````````
XXXX/XX-123456 | [Endless_Text up to ~50k characters]

在作为文本的叙述字段中，各个条目（当不同的代理对案件做了某事时）以条目日期开头，后跟两个空格（即'dd/mm/yyyy '），日期值随着同一字段中的每个条目而变化。

换句话说，在寻找更好的分隔符之后，我唯一可以使用的就是这种格式的字符串，因此我需要识别叙述文本中格式（掩码会是更好的单词吗？）匹配的多个位置'dd/mm/yyyy '。

我可以识别多次出现的一致字符串，没有问题，但它在我本质上寻找的地方识别它：

'%[0-9][0-9]/[0-9][0-9]/[0-9][0-9][0-9][0-9] %'

PATINDEX当然返回这个的第一次出现/位置，但据我所知，没有办法“修改”这个（即创建的函数）以允许拾取这个的其余出现/位置我们可以CHARINDEX（因为PATINDEX没有起始位置参数）。

为了清楚起见，我并不是在寻找代码来直接分隔它，因为我需要进一步操作每个条目，因此它纯粹是我正在寻找的叙述文本中多次出现字符串的位置。

任何帮助将非常感激。

为了清楚起见，没有选项可以执行此预导入操作，因此需要对此登陆数据进行此操作。

期望的输出是

 Case_Reference1 | 1st_Position_of_Delimiter_String  
 Case_Reference1 | 2nd_Position_of_Delimiter_String  
 Case_Reference2 | 1st_Position_of_Delimiter_String  
 Case_Reference2 | 2nd_Position_of_Delimiter_String  
 Case_Reference2 | 3rd_Position_of_Delimiter_String  

Answer 1

您可以使用递归 CTE 来解决这个问题

DECLARE @tbl TABLE (Case_Reference NVARCHAR(MAX),Narrative NVARCHAR(MAX));
INSERT INTO @tbl VALUES
 (N'C1',N'01/02/2000  Some text with     blanks 02/03/2000  More text 03/04/2000  An even more')
,(N'C2',N'01/02/2000  Test for C2 02/03/2000  One more for C2 03/04/2000  An even more 04/05/2000  Blah')
,(N'C3',N'01/02/2000  Test for C3 02/03/2000  One more for C3 03/04/2000  An even more')
 ;

WITH recCTE AS
(
    SELECT 1 AS Step,Case_Reference,Narrative,CAST(1 AS BIGINT) AS StartsAt,NewPos.EndsAt+10 AS EndsAt,LEN(Narrative) AS MaxLen
          ,SUBSTRING(Narrative,NewPos.EndsAt+10+1,999999) AS RestString
    FROM @tbl AS tbl
    CROSS APPLY(SELECT PATINDEX('%[0-3][0-9]/[0-1][0-9]/[1-2][0-9][0-9][0-9]  %',SUBSTRING(Narrative,12,9999999))) AS NewPos(EndsAt)

    UNION ALL

    SELECT r.Step+1,r.Case_Reference,r.Narrative,r.EndsAt+1,CASE WHEN NewPos.EndsAt>0 THEN r.EndsAt+NewPos.EndsAt+10 ELSE r.MaxLen END,r.MaxLen
          ,SUBSTRING(r.RestString,NewPos.EndsAt+10+1,999999) 
    FROM recCTE AS r
    CROSS APPLY(SELECT PATINDEX('%[0-3][0-9]/[0-1][0-9]/[1-2][0-9][0-9][0-9]  %',SUBSTRING(r.RestString,12,99999999))) AS NewPos(EndsAt)
    WHERE r.EndsAt<r.MaxLen
)
SELECT Step,Case_Reference,StartsAt,EndsAt
      ,SUBSTRING(Narrative,StartsAt,EndsAt-StartsAt+1) AS OutputString 
FROM recCTE

ORDER BY Case_Reference,Step

结果

+------+----------------+----------+--------+---------------------------------------+
| Step | Case_Reference | StartsAt | EndsAt | OutputString                          |
+------+----------------+----------+--------+---------------------------------------+
| 1    | C1             | 1        | 38     | 01/02/2000  Some text with     blanks |
+------+----------------+----------+--------+---------------------------------------+
| 2    | C1             | 39       | 60     | 02/03/2000  More text                 |
+------+----------------+----------+--------+---------------------------------------+
| 3    | C1             | 61       | 84     | 03/04/2000  An even more              |
+------+----------------+----------+--------+---------------------------------------+
| 1    | C2             | 1        | 24     | 01/02/2000  Test for C2               |
+------+----------------+----------+--------+---------------------------------------+
| 2    | C2             | 25       | 52     | 02/03/2000  One more for C2           |
+------+----------------+----------+--------+---------------------------------------+
| 3    | C2             | 53       | 77     | 03/04/2000  An even more              |
+------+----------------+----------+--------+---------------------------------------+
| 4    | C2             | 78       | 93     | 04/05/2000  Blah                      |
+------+----------------+----------+--------+---------------------------------------+
| 1    | C3             | 1        | 24     | 01/02/2000  Test for C3               |
+------+----------------+----------+--------+---------------------------------------+
| 2    | C3             | 25       | 52     | 02/03/2000  One more for C3           |
+------+----------------+----------+--------+---------------------------------------+
| 3    | C3             | 53       | 76     | 03/04/2000  An even more              |
+------+----------------+----------+--------+---------------------------------------+