How to find specific VALUE to specific STRING location in different strings

Question

I have a sting like this
,x,x,y,x,x,O,x,y
that matches to its values in an other sting like this
0~1~b~~z~XY~1~7.
The value \"O\" can switch its position in

Answer 1

This is a JSON based solution:

Edit: fastest approach (needs v2016) -> removed the XQuery based solution

DECLARE @string1 VARCHAR(1000) = ',x,x,x,x,x,O,x,y',
        @string2 VARCHAR(1000) = '0~1~b~~z~XY~1~7';

SELECT s2.[value]
FROM OPENJSON('["' + REPLACE(@string1,',','","') + '"]') AS s1
CROSS APPLY OPENJSON('["' + REPLACE(@string2,'~','","') + '"]') AS s2 
WHERE s1.[value]='O' AND s2.[key]=s1.[key]-1;

The idea in short: By replacing the delimiters we transform your delimited strings in JSON-arrays and use JSON's abilities to find an element's position and use this position to fetch another element.

UPDATE

I did some performance tests and found, that the XQuery solution is performing rather badly. With a small string of max 10 elements this is okay, but with longer strings (tested with 100 elements) this performs rather slow...

The test code, if interested:

DECLARE @i INT=1
       ,@CountElements INT=5 --Use higher values here
       ,@CountRows INT=500;

DECLARE @tbl TABLE(ID INT IDENTITY, i1t90 INT, s1 VARCHAR(500),s2 VARCHAR(500));

DECLARE @TemplateString VARCHAR(1000);
WHILE @i<@CountElements
BEGIN
    SET @TemplateString = CONCAT(@TemplateString,@i,'~');
    SET @i=@i+1;
END

SET @i=1;
WHILE @i<@CountRows
BEGIN
    INSERT INTO @tbl(i1t90, s1,s2) 
    SELECT
     ISNULL(NULLIF(@i%@CountElements,0),@CountElements)
    ,STUFF(REPLICATE(',x',@CountElements),(ISNULL(NULLIF(@i%@CountElements,0),@CountElements))*2,1,'O')
    ,CONCAT(@TemplateString,@i)

    SET @i=@i+1;
END

DECLARE @d DATETIME2=SYSUTCDATETIME();

SELECT t.*
      ,B.PosO
      ,A.y.value('(/y[sql:column("B.PosO")]/text())[1]','nvarchar(100)') AS FoundValue
INTO #t1
FROM @tbl t 
CROSS APPLY
(       
    SELECT (SELECT CAST('<x>' + REPLACE(s1,',','</x><x>') + '</x>' AS XML))
          ,(SELECT CAST('<y>' + REPLACE(s2,'~','</y><y>') + '</y>' AS XML))) AS A(x,y)
CROSS APPLY(SELECT A.x.value('count(/x[. << (/x[text()="O"])[1]])','int')) B(PosO);

SELECT 'XML based new', DATEDIFF(MILLISECOND,@d,SYSUTCDATETIME());

SET @d=SYSUTCDATETIME();

SELECT *
INTO #t2
FROM @tbl
CROSS APPLY dbo.delimitedSplit8K(s2,'~') AS s
WHERE s.itemNumber = 
(
  SELECT TOP (1) s1.itemNumber -- TOP (1) until we know about dupicates
  FROM   dbo.delimitedSplit8K(s1,',') AS s1
  WHERE  s1.item = 'O'
)-1;

SELECT 'Splitter based',DATEDIFF(MILLISECOND,@d,SYSUTCDATETIME());

SELECT * FROM #t1;
SELECT * FROM #t2;

DROP TABLE #t1;
DROP TABLE #t2;

The splitter-based approach is about 8 times faster in my tests...

UPDATE 2: JSON-splitter (needs v2016+)

This approach is about 5 times faster then the splitter based approach:

SELECT t.*
      ,s2.[key] +1 AS PosO --zero based index
      ,s2.[value] AS FoundValue  
INTO #t3
FROM @tbl t
CROSS APPLY OPENJSON('["' + REPLACE(s1,',','","') + '"]') AS s1
CROSS APPLY OPENJSON('["' + REPLACE(s2,'~','","') + '"]') AS s2 
WHERE s1.[value]='O' AND s2.[key]=s1.[key]-1;

Answer 2

Grab a copy of DelimitedSplit8K then you can do this:

DECLARE @string1 VARCHAR(1000) = ',x,x,y,x,x,O,x,y',
        @string2 VARCHAR(1000) = '0~1~b~~z~XY~1~7';

DECLARE @search VARCHAR(1000) = 'O'; -- best as a variable/parameter

SELECT *
FROM dbo.delimitedSplit8K(@string2,'~') AS s
WHERE s.itemNumber = 
(
  SELECT TOP (1) s2.itemNumber -- TOP (1) until we know about dupicates
  FROM   dbo.delimitedSplit8K(@string1,',') AS s2
  WHERE  s2.item = @search
)-1;

Returns:

ItemNumber           Item
-------------------- -------
6                    XY