轉換逗號分隔字符串轉換成XML序列號爲2005

Question

我使用SQL Server 2005中我有以下幾點：

DECLARE @list NVARCHAR(MAX) 
DECLARE @xml XML 

SET @list = 'aa,bb,cc,dd,ee' 

我想從與@list數據填寫@xml格式如下：

<row seq="1" col1="aa" /> 
<row seq="2" col1="bb" /> 
<row seq="3" col1="cc" /> 
<row seq="4" col1="dd" /> 

我試圖@list轉換成XML字符串如下：

SET @xml = '<row>' + REPLACE(@list, ',', '</row><row>') + '</row>' 

一第二則試圖尋找在可以添加序列號爲行@ xml.query方法FLWOR表達式，但我的運氣爲有SQL Server 2005中沒有讓條款。任何人都可以給我一個提示/解決方法嗎？謝謝。

Answer 1

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 

Answer 2

說實話，當我看着在第一次scSimon的回答中，我不喜歡它。我曾與CROSS一些不愉快的經歷湊過去指數炸燬（我結束了一個十億行的表:-)）。所以，我決定用一個更全面的方法如下所示： 1.功能，以逗號分隔的列表轉換成XML：

CREATE FUNCTION [dbo].[Delimited2XML](@pList NVARCHAR(MAX), @pDelimiter NCHAR(1)) 
RETURNS XML 
AS 
BEGIN 
    DECLARE @res NVARCHAR(MAX)  
    DECLARE @LEN INT 
    SET @LEN = LEN(@pList) 

    SET @res = '<root>' 

    IF (@pList IS NOT NULL AND 
     @LEN > 0 AND 
     @pDelimiter IS NOT NULL AND 
     LEN(@pDelimiter) > 0) 
    BEGIN 
     DECLARE @startIdx INT 
     DECLARE @curIdx INT 
     SET @startIdx = 1 
     SET @curIdx = 1 

     DECLARE @i INT 
     SET @i = 0 

     WHILE @curIdx > 0 
     BEGIN 
      SET @i = @i + 1; 
      SET @curIdx = CHARINDEX(@pDelimiter, @pList, @startIdx /*start_location*/) 

      IF (@curIdx > 0) 
      BEGIN 
       -- create a xml node with this format: <row seq="i" item="item_i" /> 
       SET @res = @res + ('<row Seq="' + LTRIM(STR(@i)) + '" Item="' + SUBSTRING(@pList, @startIdx /*start*/, @curIdx - @startIdx /*length*/) + '" />') 
       SET @startIdx = @curIdx + 1 
      END 
      ELSE 
      BEGIN 
       SET @res = @res + ('<row Seq="' + LTRIM(STR(@i)) + '" Item="' + SUBSTRING(@pList, @startIdx /*start*/, @LEN /*length*/) + '" />') 
      END 
     END 

    END 

    SET @res = @res + '</root>' 
    RETURN CAST(@res AS XML) 
END 

功能，以XML轉換爲表：

CREATE FUNCTION [DBO] [DelimitedSplit]（@ pstring類型NVARCHAR（MAX），@pDelimiter NCHAR（1）） RETURNS TABLE AS RETURN WITH TDATA AS （ SELECT dbo.Delimited2XML（@ pString，@pDelimiter） AS XMLDATA ） SELECT Tab.XMLCol.value（ '@序列'， 'INTEGER'）爲SEQ， Tab.XMLCol.value（ '@項目'， 'NVARCHAR（MAX）'）爲項目 FROM TDATA CROSS APPLY XMLData.nodes（ '/根/行'）AS選項卡（XMLCol）

我然後測試了兩個函數，DelimitedSplit（）和DelimitedSplit8K（），與具有1200+項的字符串。 DelimitedSplit（）花了240毫秒來完成，而DelimitedSplit8K（）只花了20毫秒，DelimitedSplit的僅有8％（）的時間。所以，DelimitedSplit8K（）具有更好的性能。