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

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 the string, as will the value in the other string.
The value "O" is in the 6th position so the expectet result would be "XY".
The first string always begins with a "," before each value. The second string starts first with the value followed by the "~".
"O" is a given value which will not change, so I always have to finde the given value for the position wher "O" is, in the second string.
This ist what I am expexting:
,x,x,y,x,x,O,x,y
0~1~b~~z~XY~1~7
O=XY
,x,O,y,x,x,y,x,y
0~1~b~~z~XY~1~7
O=1
Thank you.

Answer 1

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

Answer 2

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;