我有一个这样的SQL表:

| SomeID         | OtherID     | Data
+----------------+-------------+-------------------
| abcdef-.....   | cdef123-... | 18,20,22
| abcdef-.....   | 4554a24-... | 17,19
| 987654-.....   | 12324a2-... | 13,19,20

是否有一个查询,我可以执行查询,如SELECT OtherID, SplitData where SomeID = 'abcdef-.......,返回单独的行,就像这样:

| OtherID     | SplitData
+-------------+-------------------
| cdef123-... | 18
| cdef123-... | 20
| cdef123-... | 22
| 4554a24-... | 17
| 4554a24-... | 19

基本上把我的数据在逗号处分割成单独的行?

我知道将逗号分隔的字符串存储到关系数据库中听起来很愚蠢,但消费者应用程序中的正常用例使这种方法非常有用。

我不想在应用程序中进行拆分,因为我需要分页,所以我想在重构整个应用程序之前探索选项。

它是SQL Server 2008(非r2)。


当前回答

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

其他回答

很晚了,但是试试这个:

SELECT ColumnID, Column1, value  --Do not change 'value' name. Leave it as it is.
FROM tbl_Sample  
CROSS APPLY STRING_SPLIT(Tags, ','); --'Tags' is the name of column containing comma separated values

所以我们有了这个: tbl_Sample:

ColumnID|   Column1 |   Tags
--------|-----------|-------------
1       |   ABC     |   10,11,12    
2       |   PQR     |   20,21,22

运行此查询后:

ColumnID|   Column1 |   value
--------|-----------|-----------
1       |   ABC     |   10
1       |   ABC     |   11
1       |   ABC     |   12
2       |   PQR     |   20
2       |   PQR     |   21
2       |   PQR     |   22

谢谢!

通过创建这个分割字符串的函数([DelimitedSplit]),可以对SELECT执行OUTER APPLY。

CREATE FUNCTION [dbo].[DelimitedSplit]
--===== 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 INNER JOIN E1 b ON b.N = a.N), --10E+2 or 100 rows
       E4(N) AS (SELECT 1 FROM E2 a INNER JOIN E2 b ON b.N = a.N), --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
;

TEST

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';

SELECT
 *
FROM #Testdata
OUTER APPLY [dbo].[DelimitedSplit](String,',');

DROP TABLE #Testdata;

结果

SomeID  OtherID String      ItemNumber  Item
1       9       18,20,22    1           18
1       9       18,20,22    2           20
1       9       18,20,22    3           22
2       8       17,19       1           17
2       8       17,19       2           19
3       7       13,19,20    1           13
3       7       13,19,20    2           19
3       7       13,19,20    3           20
4       6       1   
9       11      1,2,3,4     1           1
9       11      1,2,3,4     2           2
9       11      1,2,3,4     3           3
9       11      1,2,3,4     4           4
;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…

select t.OtherID,x.Kod
    from testData t
    cross apply (select Code from dbo.Split(t.Data,',') ) x

我知道它有很多答案,但我想写我的版本的分裂函数像其他人和像string_split SQL Server 2016本机函数。

create function [dbo].[Split]
(
    @Value nvarchar(max),
    @Delimiter nvarchar(50)
)
returns @tbl table
(
    Seq int primary key identity(1, 1),
    Value nvarchar(max)
)
as begin
    declare @Xml xml = cast('<d>' + replace(@Value, @Delimiter, '</d><d>') + '</d>' as xml);

    insert into @tbl
            (Value)
    select  a.split.value('.', 'nvarchar(max)') as Value
    from    @Xml.nodes('/d') a(split);
    
    return;
end;

Seq列是支持快速连接其他实表或Split函数返回表的主键。 使用XML函数支持大数据(当你有大数据时,循环版本会显著变慢)

这是问题的答案。

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';


select  t.SomeID, t.OtherID, s.Value
from    Testdata t
        cross apply dbo.Split(t.String, ',') s;

--Output
SomeID  OtherID Value
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

加入Split与其他Split

declare @Names nvarchar(max) = 'a,b,c,d';
declare @Codes nvarchar(max) = '10,20,30,40';

select  n.Seq, n.Value Name, c.Value Code
from    dbo.Split(@Names, ',') n
        inner join dbo.Split(@Codes, ',') c on n.Seq = c.Seq;

--Output
Seq Name    Code
1   a       10
2   b       20
3   c       30
4   d       40

分开两次

declare @NationLocSex nvarchar(max) = 'Korea,Seoul,1;Vietnam,Kiengiang,0;China,Xian,0';

with rows as
(
    select  Value
    from    dbo.Split(@NationLocSex, ';')
)
select  rw.Value r, cl.Value c
from    rows rw
        cross apply dbo.Split(rw.Value, ',') cl;

--Output
r                       c
Korea,Seoul,1           Korea
Korea,Seoul,1           Seoul
Korea,Seoul,1           1
Vietnam,Kiengiang,0     Vietnam
Vietnam,Kiengiang,0     Kiengiang
Vietnam,Kiengiang,0     0
China,Xian,0            China
China,Xian,0            Xian
China,Xian,0            0

分割成列

declare @Numbers nvarchar(50) = 'First,Second,Third';

with t as
(
    select  case when Seq = 1 then Value end f1,
            case when Seq = 2 then Value end f2,
            case when Seq = 3 then Value end f3
    from    dbo.Split(@Numbers, ',')
)
select  min(f1) f1, min(f2) f2, min(f3) f3
from    t;

--Output
f1      f2      f3
First   Second  Third

按范围生成行


declare @Ranges nvarchar(50) = '1-2,4-6';

declare @Numbers table (Num int);
insert into @Numbers values (1),(2),(3),(4),(5),(6),(7),(8);

with t as
(
    select  r.Seq, r.Value,
            min(case when ft.Seq = 1 then ft.Value end) ValueFrom,
            min(case when ft.Seq = 2 then ft.Value end) ValueTo
    from    dbo.Split(@Ranges, ',') r
            cross apply dbo.Split(r.Value, '-') ft
    group by r.Seq, r.Value
)
select  t.Seq, t.Value, t.ValueFrom, t.ValueTo, n.Num
from    t
        inner join @Numbers n on n.Num between t.ValueFrom and t.ValueTo;

--Output
Seq Value   ValueFrom   ValueTo Num
1   1-2     1           2       1
1   1-2     1           2       2
2   4-6     4           6       4
2   4-6     4           6       5
2   4-6     4           6       6