SQL - Get specific element from an array - arrays

Question

Suppose I have 2 variables that look like an array:
declare #code nvarchar(200) =
',10501,10203,10491,10490,10091,10253,10008,10020,10570,10499,';
declare #value nvarchar(200) =
'True~~100000006~Digital~0~0~~1388.76~Completed~True';
I need to find if #code contains 10490 (for example) and if it does, I need to find a corresponding value (by its index) in #value variable which would be Digital since 10490 is the 4th element in #code array and 4th element of #value array is Digital (note that the 2nd element of the #value array is NULL.
Disclaimer:
#code array will ALWAYS contain unique values. It's not possible to have more than 1 10490 for example.
#code array will always start and end with ','.
Number of elements in #code and #value will always be the same if you take 1st and last comma off the #code variable.
I cannot use functions or stored procedures, so everything needs to be done as part of 1 query.

Answer 1

I think you know, that this is a very bad design... If you can change this, you really should. But this can be solved:
declare #code nvarchar(200) =
',10501,10203,10491,10490,10091,10253,10008,10020,10570,10499,';
declare #value nvarchar(200) =
'True~~100000006~Digital~0~0~~1388.76~Completed~True';
--The query will cast both strings to a splittable XML
--The query('/x[text()]') will remove empty entries (leading and trailing comma)
--(...assuming there will never be an empty entry in #code)
--Then it will read a derived numbered list from both
--finally it will join both lists on their PartIndex
WITH Casted AS
(
SELECT CAST('<x>' + REPLACE(#code,',','</x><x>') + '</x>' AS XML).query('/x[text()]') AS CodeXml
,CAST('<x>' + REPLACE(#value,'~','</x><x>') + '</x>' AS XML) AS ValueXml
)
,CodeDerived AS
(
SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS PartIndex
,x.value('text()[1]','nvarchar(max)') AS CodePart
FROM Casted
CROSS APPLY CodeXml.nodes('/x') A(x)
)
,ValueDerived AS
(
SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS PartIndex
,x.value('text()[1]','nvarchar(max)') AS ValuePart
FROM Casted
CROSS APPLY ValueXml.nodes('/x') A(x)
)
SELECT cd.PartIndex
,CodePart
,ValuePart
FROM CodeDerived cd
INNER JOIN ValueDerived vd ON cd.PartIndex=vd.PartIndex
The result
inx CodePart ValuePart
1 10501 True
2 10203 NULL
3 10491 100000006
4 10490 Digital
5 10091 0
6 10253 0
7 10008 NULL
8 10020 1388.76
9 10570 Completed
10 10499 True
Just add a simple WHERE to reduce this to the one value you need.
Disclaimer: it is not guaranteed, that the numbering with ROW_NUMBER and ORDER BY (SELECT NULL) will ever return the correct sequence, but for a better chance you'd need SQL Server 2016+. For more details: read this link and the other contributions there

Answer 2

Here are two possibilities. In your case I would even try to merge it into one WHILE loop.
SQL Server 2016 and above
(compatibility level 130 and up) you can use built in function STRING_SPLIT
DECLARE #code nvarchar(200) =
',10501,10203,10491,10490,10091,10253,10008,10020,10570,10499,';
DECLARE #value nvarchar(200) =
'True~~100000006~Digital~0~0~~1388.76~Completed~True';
DECLARE #valuetosearch nvarchar(200) = '10490'
SELECT value FROM
(
SELECT value ,ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS 'idx'
FROM STRING_SPLIT ( #value , '~' )
) AS x2
WHERE x2.idx =
(
SELECT idx-1 FROM
(
SELECT value ,ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS 'idx'
FROM STRING_SPLIT ( #code , ',' )
) AS x1
WHERE x1.[value] = #valuetosearch
)
For earlier versions of SQL Server:
DECLARE #code nvarchar(200) =
',10501,10203,10491,10490,10091,10253,10008,10020,10570,10499,';
DECLARE #value nvarchar(200) =
'True~~100000006~Digital~0~0~~1388.76~Completed~True';
DECLARE #valuetosearch nvarchar(200) = '10490'
DECLARE #codetbl AS TABLE (idx int IDENTITY(1,1)
,code nvarchar(200))
DECLARE #valuetbl AS TABLE (idx int IDENTITY(1,1)
,value nvarchar(200))
DECLARE #name nvarchar(200)
DECLARE #pos int
WHILE CHARINDEX(',', #code) > 0
BEGIN
SELECT #pos = CHARINDEX(',', #code)
SELECT #name = SUBSTRING(#code, 1, #pos-1)
INSERT INTO #codetbl
SELECT #name
SELECT #code = SUBSTRING(#code, #pos+1, LEN(#code)-#pos)
END
INSERT INTO #codetbl
SELECT #code
WHILE CHARINDEX('~', #value) > 0
BEGIN
SELECT #pos = CHARINDEX('~', #value)
SELECT #name = SUBSTRING(#value, 1, #pos-1)
INSERT INTO #valuetbl
SELECT #name
SELECT #value = SUBSTRING(#value, #pos+1, LEN(#value)-#pos)
END
INSERT INTO #valuetbl
SELECT #value
SELECT value FROM #valuetbl
WHERE idx = (SELECT idx-1 FROM #codetbl WHERE code = #valuetosearch)

Answer 3

You may need to add some code for when #tofind is not found
declare #code nvarchar(200) =
',10501,10203,10491,10490,10091,10253,10008,10020,10570,10499,';
declare #value nvarchar(200) =
'True~~100000006~Digital~0~0~~1388.76~Completed~True';
declare #tofind nvarchar(200) = '10490';
--select left(#code,CHARINDEX(#tofind,#code))
--select len(left(#code,CHARINDEX(#tofind,#code))) - LEN( REPLACE( left(#code,CHARINDEX(#tofind,#code)) , ',', ''))
declare #nth int;
set #nth = len(left(#code,CHARINDEX(#tofind,#code))) - LEN( REPLACE( left(#code,CHARINDEX(#tofind,#code)) , ',', ''))
declare #SplitOn nvarchar = '~';
declare #RowData nvarchar(200) = #value + '~';
declare #Cnt int = 1
While (Charindex(#SplitOn,#RowData)>0) and #Cnt < #nth
Begin
Set #RowData = Substring(#RowData,Charindex(#SplitOn,#RowData)+1,len(#RowData))
Set #Cnt = #Cnt + 1
End
Select --Data = ltrim(rtrim(#RowData)),
Case when ltrim(rtrim(#RowData)) = '' then null else
LEFT(ltrim(rtrim(#RowData)) , CHARINDEX('~',ltrim(rtrim(#RowData))) -1)
end as Result

Answer 4

This should be quite simple. If performance is important I would suggest splitting the strings using DelimitedSplit8K. Here's a simple, high-performing solution:
DECLARE #searchFor INT = 10490;
SELECT code = s1.item, s2.item
FROM dbo.DelimitedSplit8K(#code,',') s1
JOIN dbo.DelimitedSplit8K(#value,'~') s2 ON s2.ItemNumber = s1.ItemNumber-1
WHERE s1.Item = #searchFor;
Results:
code item
---------- ------------
10490 Digital