如何在定界符之间多次提取字符串的一部分并输入到新列 T-SQL

Question

我想从一个具有多个相同分隔符的值中多次提取字符串的一部分，并将提取的字符串放入新列中。

这是我正在使用的数据示例（这些文件夹路径可能更长，具体取决于文件夹的深度）：

文件夹路径：

Q:\downloads\extraction\bee\honey\
Q:\desktop\chocolate\london\time\spring\
Q:\documents\cars\astonmartin\vanquish\

我想从左边的分隔符之间提取整个字符串，并将它们放入字符串不同阶段的新列中，例如

FolderPath	RootDirectory	SubDirectory	SubSubDirectory
Q:\documents\cars\astonmartin\vanquish\	Q:\documents	Q:\documents\cars	Q:\documents\cars\astonmartin

我只是想知道这是否可行，尤其是当文件夹名称具有不同长度的所有类型时。

如有任何帮助，我将不胜感激 - 谢谢！

Answer 1

已更新（使用第二个解决方案）

解决方案 #1 - Charindex + 级联应用：

--==== Sample Data
DECLARE @folders TABLE (Folder VARCHAR(1000));
INSERT  @folders VALUES
('Q:\downloads\extraction\bee\honey\'),
('Q:\desktop\chocolate\london\time\spring\'),
('Q:\documents\cars\astonmartin\vanquish\');

SELECT      FolderParse.*
FROM        @folders AS f
CROSS APPLY
(
  SELECT
    FolderPath      = f.Folder,
    RootDirectory   = SUBSTRING(f.Folder, 1, p2.Pos-2),
    SubDirectory    = SUBSTRING(f.Folder, 1, p3.Pos-1),
    SubSubDirectory = SUBSTRING(f.Folder, 1, p4.Pos-1)
  FROM        (VALUES(CHARINDEX('\',f.Folder)))          AS p1(Pos)
  CROSS APPLY (VALUES(CHARINDEX('\',f.Folder,p1.Pos+1))) AS p2(Pos)
  CROSS APPLY (VALUES(CHARINDEX('\',f.Folder,p2.Pos+1))) AS p3(Pos)
  CROSS APPLY (VALUES(CHARINDEX('\',f.Folder,p3.Pos+1))) AS p4(Pos)
) AS folderParse;

结果：

FolderPath                                RootDirectory  SubDirectory            SubSubDirectory
----------------------------------------- -------------- ----------------------- ---------------------------------
Q:\downloads\extraction\bee\honey\        Q:\downloads   Q:\downloads\extraction Q:\downloads\extraction\bee
Q:\desktop\chocolate\london\time\spring\  Q:\desktop     Q:\desktop\chocolate    Q:\desktop\chocolate\london
Q:\documents\cars\astonmartin\vanquish\   Q:\documents   Q:\documents\cars       Q:\documents\cars\astonmartin

解决方案 #2 - Tally Table:

第一个解决方案是可行的方法，但当您需要更深入时，第二个解决方案更好。为此，您需要获取 fnTally.

的副本

以下是针对一个字符串执行此操作的方法：

DECLARE @string VARCHAR(1000) =  'Q:\documents\cars\astonmartin\vanquish\';

SELECT
  FolderPath      = @string,
  RootDirectory   = MAX(CASE f.RN WHEN 1 THEN f.FPath END),
  SubDirectory    = MAX(CASE f.RN WHEN 2 THEN f.FPath END),
  SubSubDirectory = MAX(CASE f.RN WHEN 3 THEN f.FPath END)
FROM
(
  SELECT      ROW_NUMBER() OVER (ORDER BY t.N), SUBSTRING(@string,1,t.N+2)
  FROM        (VALUES(SUBSTRING(@string,4,1000))) AS s(Txt)
  CROSS APPLY dbo.fnTally(1,LEN(s.Txt))           AS t
  WHERE       SUBSTRING(s.Txt,t.N,1) = '\'
) AS f(RN,FPath);

Returns:

FolderPath                               RootDirectory      SubDirectory          SubSubDirectory
---------------------------------------- ------------------ --------------------- --------------------------------
Q:\documents\cars\astonmartin\vanquish\  Q:\documents       Q:\documents\cars     Q:\documents\cars\astonmartin

反对 table:

--==== Sample Data
DECLARE @folders TABLE (Folder VARCHAR(1000));
INSERT  @folders VALUES
('Q:\downloads\extraction\bee\honey\'),
('Q:\desktop\chocolate\london\time\spring\'),
('Q:\documents\cars\astonmartin\vanquish\');

--==== Solution
SELECT DirectoryParse.* 
FROM   @folders AS fld
CROSS APPLY
(
  SELECT
    FolderPath      = fld.Folder,
    RootDirectory   = MAX(CASE f.RN WHEN 1 THEN f.FPath END),
    SubDirectory    = MAX(CASE f.RN WHEN 2 THEN f.FPath END),
    SubSubDirectory = MAX(CASE f.RN WHEN 3 THEN f.FPath END)
  FROM
  (
    SELECT      ROW_NUMBER() OVER (ORDER BY t.N), SUBSTRING(fld.Folder,1,t.N+2)
    FROM        (VALUES(SUBSTRING(fld.Folder,4,1000))) AS s(Txt)
    CROSS APPLY dbo.fnTally(1,LEN(s.Txt))           AS t
    WHERE       SUBSTRING(s.Txt,t.N,1) = '\'
  ) AS f(RN,FPath)
) AS DirectoryParse;

结果：

FolderPath                                RootDirectory  SubDirectory            SubSubDirectory
----------------------------------------- -------------- ----------------------- ---------------------------------
Q:\downloads\extraction\bee\honey\        Q:\downloads   Q:\downloads\extraction Q:\downloads\extraction\bee
Q:\desktop\chocolate\london\time\spring\  Q:\desktop     Q:\desktop\chocolate    Q:\desktop\chocolate\london
Q:\documents\cars\astonmartin\vanquish\   Q:\documents   Q:\documents\cars       Q:\documents\cars\astonmartin

如何在定界符之间多次提取字符串的一部分并输入到新列 T-SQL

How to extract part of a string numerous times between delimiters and input into new columns T-SQL

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charindex