下面是一個使用分裂功能的方式......
DECLARE @list NVARCHAR(MAX)
DECLARE @xml XML
SET @list = 'aa,bb,cc,dd,ee'
;with cteSplit as(
select * from dbo.DelimitedSplit8K(@list,',')),
cteFinal as(
select
'<row seq="' + cast(ItemNumber as varchar(64)) + '" col1="' + Item + '" />' as Item
from cteSplit)
select Item from cteFinal --for XML AUTO
Here is the function這已被證明是分割字符串的快速方法:
CREATE FUNCTION [dbo].[DelimitedSplit8K] (@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.
SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY l.N1),
Item = SUBSTRING(@pString, l.N1, l.L1)
FROM cteLen l
;
GO
感謝您的回答,西蒙。在這裏使用了函數ROW_NUMBER()OVER ...。我懷疑它在某些特殊情況下可能無法保留原始列表順序,儘管其結果似乎是正確的? –
它會根據你的逗號分隔字符串 – scsimon
在cteTally你的元素的順序保持秩序,我覺得應該用函數LEN(),而不是DATALENGTH(),如LEN()可以同NVARCHAR工作(X)和VARCHAR(x),並在兩種情況下都給出正確的結果。以防萬一我們想將參數更改爲NVARCHAR(x)。 –