;WITH tmp(SomeID, OtherID, DataItem, Data) as (
    SELECT SomeID, OtherID, LEFT(Data, CHARINDEX(',',Data+',')-1),
        STUFF(Data, 1, CHARINDEX(',',Data+','), '')
FROM Testdata
WHERE Data > ''
)
SELECT SomeID, OtherID, Data
FROM tmp
ORDER BY SomeID

仅对上述查询进行了微小的修改…

当使用这种方法时，您必须确保您的值中没有包含非法XML - user1151923

我总是使用XML方法。确保使用VALID XML。我有两个函数在有效的XML和文本之间转换。(我倾向于去掉回车，因为我通常不需要它们。

CREATE FUNCTION dbo.udf_ConvertTextToXML (@Text varchar(MAX)) 
    RETURNS varchar(MAX)
AS
    BEGIN
        SET @Text = REPLACE(@Text,CHAR(10),'');
        SET @Text = REPLACE(@Text,CHAR(13),'');
        SET @Text = REPLACE(@Text,'<','&lt;');
        SET @Text = REPLACE(@Text,'&','&amp;');
        SET @Text = REPLACE(@Text,'>','&gt;');
        SET @Text = REPLACE(@Text,'''','&apos;');
        SET @Text = REPLACE(@Text,'"','&quot;');
    RETURN @Text;
END;


CREATE FUNCTION dbo.udf_ConvertTextFromXML (@Text VARCHAR(MAX)) 
    RETURNS VARCHAR(max)
AS
    BEGIN
        SET @Text = REPLACE(@Text,'&lt;','<');
        SET @Text = REPLACE(@Text,'&amp;','&');
        SET @Text = REPLACE(@Text,'&gt;','>');
        SET @Text = REPLACE(@Text,'&apos;','''');
        SET @Text = REPLACE(@Text,'&quot;','"');
    RETURN @Text;
END;

你可以使用SQL Server中的递归函数:

示例表:

CREATE TABLE Testdata
(
    SomeID INT,
    OtherID INT,
    String VARCHAR(MAX)
);

INSERT Testdata SELECT 1,  9, '18,20,22';
INSERT Testdata SELECT 2,  8, '17,19';
INSERT Testdata SELECT 3,  7, '13,19,20';
INSERT Testdata SELECT 4,  6, '';
INSERT Testdata SELECT 9, 11, '1,2,3,4';

查询

WITH tmp(SomeID, OtherID, DataItem, String) AS
(
    SELECT
        SomeID,
        OtherID,
        LEFT(String, CHARINDEX(',', String + ',') - 1),
        STUFF(String, 1, CHARINDEX(',', String + ','), '')
    FROM Testdata
    UNION all

    SELECT
        SomeID,
        OtherID,
        LEFT(String, CHARINDEX(',', String + ',') - 1),
        STUFF(String, 1, CHARINDEX(',', String + ','), '')
    FROM tmp
    WHERE
        String > ''
)
SELECT
    SomeID,
    OtherID,
    DataItem
FROM tmp
ORDER BY SomeID;
-- OPTION (maxrecursion 0)
-- normally recursion is limited to 100. If you know you have very long
-- strings, uncomment the option

输出

 SomeID | OtherID | DataItem 
--------+---------+----------
 1      | 9       | 18       
 1      | 9       | 20       
 1      | 9       | 22       
 2      | 8       | 17       
 2      | 8       | 19       
 3      | 7       | 13       
 3      | 7       | 19       
 3      | 7       | 20       
 4      | 6       |          
 9      | 11      | 1        
 9      | 11      | 2        
 9      | 11      | 3        
 9      | 11      | 4        

可以使用以下函数提取数据

CREATE FUNCTION [dbo].[SplitString]
(    
    @RowData NVARCHAR(MAX),
    @Delimeter NVARCHAR(MAX)
)
RETURNS @RtnValue TABLE 
(
    ID INT IDENTITY(1,1),
    Data NVARCHAR(MAX)
) 
AS
BEGIN 
    DECLARE @Iterator INT;
    SET @Iterator = 1;

    DECLARE @FoundIndex INT;
    SET @FoundIndex = CHARINDEX(@Delimeter,@RowData);

    WHILE (@FoundIndex>0)
    BEGIN
        INSERT INTO @RtnValue (data)
        SELECT 
            Data = LTRIM(RTRIM(SUBSTRING(@RowData, 1, @FoundIndex - 1)));

        SET @RowData = SUBSTRING(@RowData,
                @FoundIndex + DATALENGTH(@Delimeter) / 2,
                LEN(@RowData));

        SET @Iterator = @Iterator + 1;
        SET @FoundIndex = CHARINDEX(@Delimeter, @RowData);
    END;
    
    INSERT INTO @RtnValue (Data)
    SELECT Data = LTRIM(RTRIM(@RowData));

    RETURN;
END;

;WITH tmp(SomeID, OtherID, DataItem, Data) as (
    SELECT SomeID, OtherID, LEFT(Data, CHARINDEX(',',Data+',')-1),
        STUFF(Data, 1, CHARINDEX(',',Data+','), '')
FROM Testdata
WHERE Data > ''
)
SELECT SomeID, OtherID, Data
FROM tmp
ORDER BY SomeID

仅对上述查询进行了微小的修改…

终于，SQL Server 2016结束了等待。他们引入了Split字符串函数STRING_SPLIT:

select OtherID, cs.Value --SplitData
from yourtable
cross apply STRING_SPLIT (Data, ',') cs

所有其他方法来分割字符串，如XML, tallytable, while循环等。已经被STRING_SPLIT函数破坏了。

这里有一篇关于性能比较的优秀文章:性能惊喜和假设:STRING_SPLIT。

对于旧版本，这里使用的是一个分割字符串函数(可能的最佳方法)

CREATE FUNCTION [dbo].[DelimitedSplit8K] (@pString VARCHAR(8000), @pDelimiter CHAR(1)) RETURNS TABLE WITH SCHEMABINDING AS RETURN --===== "Inline" CTE Driven "Tally Table" produces values from 0 up to 10,000... -- enough to cover NVARCHAR(4000) 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. SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY l.N1), Item = SUBSTRING(@pString, l.N1, l.L1) FROM cteLen l ;

从talley引用哦!一个改进的SQL 8K“CSV分配器”函数