sql-server - SQL Server 字符串到 m x n 表

Question

这里有很多关于在 SQL 中拆分字符串的优秀帖子。
然而，我正在寻找一个真正的字符串到表函数。
换句话说，取一个表示表(具有多行和多列)的字符串并在 SQL Server 中生成等效的表。
这意味着有一个内部分隔符和一个外部分隔符。
字符串需要被外层分隔符分割成行，然后每一行变成一组列。
我在这里找不到任何发布的内容，所以我想我会提交我的版本并征求反馈。
在我的特定使用场景中，我知道每行不超过 10 列，并且总大小在 varchar(8000) 之下。
这是 tfSplitString 函数(列出只是为了完整性；您可以根据需要使用自己的版本)，然后是 dbo.tfStringToTable10Cols 。由于我不知道列名，它们只是输出为 Col1、Col2、Col3 等。

if object_id('dbo.tfSplitString') is not null 
    exec (' DROP FUNCTION [dbo].[tfSplitString]');
go

CREATE FUNCTION [dbo].[tfSplitString]
/**********************************************************************************************************************
 Purpose:
 Split a given string at a given delimiter and return a list of the split elements (items).

 Notes:
 1.  Leading a trailing delimiters are treated as if an empty string element were present.
 2.  Consecutive delimiters are treated as if an empty string element were present between them.
 3.  Except when spaces are used as a delimiter, all spaces present in each element are preserved.
 
 select * from [dbo].[tfSplitString]('This is a test of the emergency breadcast system', ' ')
 Returns:
1   This
2   is
3   a
4   test
5   of
6   the
7   emergency
8   breadcast
9   system

 iTVF containing the following:
 ItemNumber = Element position of Item as a BIGINT (not converted to INT to eliminate a CAST)
 Item       = Element value as a VARCHAR(8000)


 CROSS APPLY Usage Examples and Tests:
--=====================================================================================================================
-- TEST 1:
-- This tests for various possible conditions in a string using a comma as the delimiter.  The expected results are
-- laid out in the comments
--=====================================================================================================================
--===== Conditionally drop the test tables to make reruns easier for testing.
     -- (this is NOT a part of the solution)
     IF OBJECT_ID('tempdb..#JBMTest') IS NOT NULL DROP TABLE #JBMTest
;
--===== Create and populate a test table on the fly (this is NOT a part of the solution).
     -- In the following comments, "b" is a blank and "E" is an element in the left to right order.
     -- Double Quotes are used to encapsulate the output of "Item" so that you can see that all blanks
     -- are preserved no matter where they may appear.
 SELECT *
   INTO #JBMTest
   FROM (                                               --# & type of Return Row(s)
         SELECT  0, NULL                      UNION ALL --1 NULL
         SELECT  1, SPACE(0)                  UNION ALL --1 b (Empty String)
         SELECT  2, SPACE(1)                  UNION ALL --1 b (1 space)
         SELECT  3, SPACE(5)                  UNION ALL --1 b (5 spaces)
         SELECT  4, ','                       UNION ALL --2 b b (both are empty strings)
         SELECT  5, '55555'                   UNION ALL --1 E
         SELECT  6, ',55555'                  UNION ALL --2 b E
         SELECT  7, ',55555,'                 UNION ALL --3 b E b
         SELECT  8, '55555,'                  UNION ALL --2 b B
         SELECT  9, '55555,1'                 UNION ALL --2 E E
         SELECT 10, '1,55555'                 UNION ALL --2 E E
         SELECT 11, '55555,4444,333,22,1'     UNION ALL --5 E E E E E 
         SELECT 12, '55555,4444,,333,22,1'    UNION ALL --6 E E b E E E
         SELECT 13, ',55555,4444,,333,22,1,'  UNION ALL --8 b E E b E E E b
         SELECT 14, ',55555,4444,,,333,22,1,' UNION ALL --9 b E E b b E E E b
         SELECT 15, ' 4444,55555 '            UNION ALL --2 E (w/Leading Space) E (w/Trailing Space)
         SELECT 16, 'This,is,a,test.'                   --E E E E
        ) d (SomeID, SomeValue)
;
--===== Split the CSV column for the whole table using CROSS APPLY (this is the solution)
 SELECT test.SomeID, test.SomeValue, split.ItemNumber, Item = QUOTENAME(split.Item,'"')
   FROM #JBMTest test
  CROSS APPLY dbo.tfSplitString(test.SomeValue,',') split
;
--=====================================================================================================================
-- TEST 2:
-- This tests for various "alpha" splits and COLLATION using all ASCII characters from 0 to 255 as a delimiter against
-- a given string.  Note that not all of the delimiters will be visible and some will show up as tiny squares because
-- they are "control" characters.  More specifically, this test will show you what happens to various non-accented 
-- letters for your given collation depending on the delimiter you chose.
--=====================================================================================================================
WITH 
cteBuildAllCharacters (String,Delimiter) AS 
(
 SELECT TOP 256 
        'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789',
        CHAR(ROW_NUMBER() OVER (ORDER BY (SELECT NULL))-1)
   FROM master.sys.all_columns
)
 SELECT ASCII_Value = ASCII(c.Delimiter), c.Delimiter, split.ItemNumber, Item = QUOTENAME(split.Item,'"')
   FROM cteBuildAllCharacters c
  CROSS APPLY dbo.tfSplitString(c.String,c.Delimiter) split
  ORDER BY ASCII_Value, split.ItemNumber
;
--===== Define I/O parameters

 */
(@pString VARCHAR(8000), @pDelimiter CHAR(1))
RETURNS TABLE WITH SCHEMABINDING AS
 RETURN
 with
  cte1(prevPos, nextPos) as (                       -- previous position of the delimiter; next position of the delimiter
      select 0, CHARINDEX(@pDelimiter, @pString)
      union all
      select nextPos, CHARINDEX(@pDelimiter, @pString, nextPos+1)
      from cte1
      where nextPos>0
     )
 select row_number() over (order by (select null)) ItemNumber
      , SUBSTRING(@pString, prevPos+1, case when nextPos=0 then len(@pString) else nextPos-(prevPos+1) end) Item
      from cte1;
GO

if object_id('dbo.tfStringToTable10Cols') is not null exec (' DROP FUNCTION [dbo].[tfStringToTable10Cols]');

go

Schema_drop_function 'tfStringToTable10Cols'
go

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO
/**
Inlined Table-valued function to deserialize a string into an n by 10 table.
Column values must not contain either the inner or outer delimiter.
Empty rows are ignored.
Note: This could trivially be converted to return more columns if a use case arises

Example:
select * from dbo.tfStringToTable20Cols('a1,b1,c1,d1,e1,f1,g1,h1,i1,j1;;,b2,c2;a3,,c3,d3,e3,f3,g3,h3,i3,j3', DEFAULT, DEFAULT)
should return

Col1 Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10
a1   b1    c1    d1   e1   f1   g1   h1   i1    j1
     b2    c2  NULL NULL NULL NULL NULL NULL  NULL
a3         c3    d3   e3   f3   g3   h3   i3    j3

*/
create function dbo.tfStringToTable10Cols
(
    @Series          varchar(8000),
    @OuterDelimiter char(1) = ';',
    @InnerDelimiter char(1) = ','
)
RETURNS TABLE
AS
RETURN
    select p.[1] Col1, p.[2] Col2, p.[3] Col3, p.[4] Col4, p.[5] Col5, p.[6] Col6, p.[7] Col7, p.[8] Col8, p.[9] Col9, p.[10] Col10
    from dbo.tfSplitString(@Series, @OuterDelimiter) as r                   -- This breaks up the strings into serialized rowstrings
    cross apply (
        select * from dbo.tfSplitString(r.Item, @InnerDelimiter) cols       -- This breaks up the rowstrings into columnNumber and columnVal rows
        pivot (Max(cols.Item)                                               -- The pivot then turns these rows into columns.  The Max() is a no-op since each columnNumber is unique
                for cols.ItemNumber in ([1], [2], [3], [4], [5], [6], [7], [8], [9], [10]))
            as tmp) as P
    where len(r.Item)>0
go


select * from dbo.tfStringToTable10Cols('a1,b1,c1,d1,e1,f1,g1,h1,i1,j1;,b2,c2;a3,,c3,d3,e3,f3,g3,h3,i3,j3', DEFAULT, DEFAULT)```

Answer 1

只是为了好玩。
如果您碰巧在 2016 年以上，您可以利用 JSON 功能，并远离您的 tfSplitString功能
示例

Declare @Series         varchar(max) = 'a1,b1,c1,d1,e1,f1,g1,h1,i1,j1;;,b2,c2;a3,,c3,d3,e3,f3,g3,h3,i3,j3'
Declare @OuterDelimiter varchar(25) = ';'
Declare @InnerDelimiter varchar(25) = ','

Select B.*
 From  (
        Select RetSeq = [Key]+1
              ,RetVal = Value
         From  OpenJSON( '["'+replace(replace(@Series,'"','\"'),@OuterDelimiter,'","')+'"]' )
       ) A
 Cross Apply (
                Select Pos1  = JSON_VALUE(S,'$[0]')
                      ,Pos2  = JSON_VALUE(S,'$[1]')
                      ,Pos3  = JSON_VALUE(S,'$[2]')
                      ,Pos4  = JSON_VALUE(S,'$[3]')
                      ,Pos5  = JSON_VALUE(S,'$[4]')
                      ,Pos6  = JSON_VALUE(S,'$[5]')
                      ,Pos7  = JSON_VALUE(S,'$[6]')
                      ,Pos8  = JSON_VALUE(S,'$[7]')
                      ,Pos9  = JSON_VALUE(S,'$[8]')
                      ,Pos10 = JSON_VALUE(S,'$[9]')
                 From  ( values ( '["'+replace(replace(A.RetVal,'"','\"'),@InnerDelimiter,'","')+'"]' ) ) A(S)
             ) B
 Where A.RetVal <>''

返回

Pos1    Pos2    Pos3    Pos4    Pos5    Pos6    Pos7    Pos8    Pos9    Pos10
a1      b1      c1      d1      e1      f1      g1      h1      i1      j1
        b2      c2      NULL    NULL    NULL    NULL    NULL    NULL    NULL
a3              c3      d3      e3      f3      g3      h3      i3      j3