T-SQL - 如何将（字符分隔）字符串拆分为行和列

Question

将字符分隔的字符串拆分为行和列的最佳方法是什么？

这是我的输入字符串：

!1;100;10;200;0;500;2;1000;30!2;100;3;500;1;2000;5

这是我想要的输出表：

Id  Value  Count
1   100    10
1   200    0
1   500    2
1   1000   30
2   100    3
2   500    1
2   2000   5

此致，

Answer 1

Jeff Moden 在 www.SQLServerCentral.com 上创建了一个名为DelimitedSplit8K 的​​拆分器函数。它需要两个参数@pString（要分割的字符串）和@pDelimiter（分隔符，在您的情况下；）。

但是，在您的情况下，您没有进行直接拆分，因此必须对其进行一些修改。事实上，我们必须进行两种不同类型的拆分。第一个正常的分裂！第二个是修改后的，使用第一个值作为第一列来获取不同的行，其余的分成对，每行一对。

先测试代码

DECLARE @splitstring varchar(8000)
SET @splitstring = '!1;100;10;200;0;500;2;1000;30!2;100;3;500;1;2000;5'
-- First use the original function to split out the groups.
-- The STUFF function removes the first ! since this is a split function
-- and if it's left we get a blank line.
SELECT FinalDelim.* 
FROM DelimitedSplit8K(STUFF(@splitstring,1,1,''),'!') AS FirstDelim
-- Here we CROSS APPLY the modified version over each of the original splits
CROSS APPLY ModifiedDelimitedSplit8K(FirstDelim.Item,';') AS FinalDelim
GO

这是 ModifiedDelimitedSplit8K 代码。

-- Based Jeff Modem's original script
CREATE FUNCTION [dbo].[ModifiedDelimitedSplit8K]
--===== Define I/O parameters
        (@pString VARCHAR(8000), @pDelimiter CHAR(1))
--WARNING!!! DO NOT USE MAX DATA-TYPES HERE!  IT WILL KILL PERFORMANCE!
RETURNS TABLE WITH SCHEMABINDING AS
 RETURN
--===== "Inline" CTE Driven "Tally Table" produces values from 1 up to 10,000...
     -- enough to cover VARCHAR(8000)
  WITH E1(N) AS (
                 SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
                 SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
                 SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
                ),                          --10E+1 or 10 rows
       E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
       E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
 cteTally(N) AS (--==== This provides the "base" CTE and limits the number of rows right up front
                     -- for both a performance gain and prevention of accidental "overruns"
                 SELECT TOP (ISNULL(DATALENGTH(@pString),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
                ),
cteStart(N1) AS (--==== This returns N+1 (starting position of each "element" just once for each delimiter)
                 SELECT 1 UNION ALL
                 SELECT t.N+1 FROM cteTally t WHERE SUBSTRING(@pString,t.N,1) = @pDelimiter
                ),
cteLen(N1,L1) AS(--==== Return start and length (for use in substring)
                 SELECT s.N1,
                        ISNULL(NULLIF(CHARINDEX(@pDelimiter,@pString,s.N1),0)-s.N1,8000)
                   FROM cteStart s
                ),
--===== Do the actual split. The ISNULL/NULLIF combo handles the length for the final element when no delimiter is found.
-- Putting this in it's own CTE since we need ItemNumber 1 for all of the rows
cteSplitString(ItemNumber, Item) AS (
     SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY l.N1),
            Item       = SUBSTRING(@pString, l.N1, l.L1)
    FROM cteLen l)
SELECT cteItem1.Item AS Id,
    cteItem2.Value,
    cteItem2.Count
FROM (SELECT Item FROM cteSplitString WHERE ItemNumber = 1) AS cteItem1
CROSS JOIN (SELECT MAX(CASE WHEN ItemNumber%2 = 0 THEN Item ELSE NULL END) AS Value,
                    MAX(CASE WHEN ItemNumber%2 = 1 THEN Item ELSE NULL END) AS Count
            FROM cteSplitString 
            WHERE ItemNumber > 1
            GROUP BY ItemNumber/2) AS cteItem2