Get characters before underscore and separated by comma from a string in SQL Server 2008 - tsql

Question

I tried this query
DECLARE #AdvancedSearchSelectedDropdownName TABLE (
SelectedIds VARCHAR(2048),
AdvanceSearchOptionTypeId INT
)
INSERT INTO #AdvancedSearchSelectedDropdownName
VALUES ('4_0,5_1,6_2,7_3', 23),
('62_3', 21), ('2_4', 23)
DECLARE #selectedIds VARCHAR(MAX) = '';
SELECT #selectedIds +=
CASE WHEN SelectedIds IS NULL
THEN #selectedIds + ISNULL(SelectedIds + ',', '')
WHEN SelectedIds IS NOT NULL
THEN SUBSTRING(SelectedIds, 0, CHARINDEX('_', SelectedIds, 0)) + ','
END
FROM #AdvancedSearchSelectedDropdownName WHERE advanceSearchOptionTypeId = 23
SELECT #selectedIds
Current output: 4,2
Required output: 4,5,6,7,2
We may have n number of comma separated values in the SelectedIds column.

Answer 1

You might go this route:
WITH Casted AS
(
SELECT *
,CAST('<x><y>' + REPLACE(REPLACE(SelectedIds,'_','</y><y>'),',','</y></x><x><y>') + '</y></x>' AS XML) SplittedToXml
FROM #AdvancedSearchSelectedDropdownName
)
SELECT *
FROM Casted;
This will return your data in this form:
<x>
<y>4</y>
<y>0</y>
</x>
<x>
<y>5</y>
<y>1</y>
</x>
<x>
<y>6</y>
<y>2</y>
</x>
<x>
<y>7</y>
<y>3</y>
</x>
Now we can grab all the x and just the first y:
WITH Casted AS
(
SELECT *
,CAST('<x><y>' + REPLACE(REPLACE(SelectedIds,'_','</y><y>'),',','</y></x><x><y>') + '</y></x>' AS XML) SplittedToXml
FROM #AdvancedSearchSelectedDropdownName
)
SELECT Casted.AdvanceSearchOptionTypeId AS TypeId
,x.value('y[1]/text()[1]','int') AS IdValue
FROM Casted
CROSS APPLY SplittedToXml.nodes('/x') A(x);
The result:
TypeId IdValue
23 4
23 5
23 6
23 7
21 62
23 2
Hint: Do not store comma delimited values!
It is a very bad idea to store your data in this format. You can use a generic format like my XML to store this or a structure of related side tables. But such construction tend to turn out as a real pain in the neck...

Answer 2

After a little re-think. Perhaps something a little more straightforward.
Now, if you have a limited number of _N
Example
;with cte as (
Select *
,RN = Row_Number() over(Order by (Select NULL))
From #AdvancedSearchSelectedDropdownName A
)
Select AdvanceSearchOptionTypeId
,IDs = replace(
replace(
replace(
replace(
replace(
stuff((Select ',' +SelectedIds From cte Where AdvanceSearchOptionTypeId=A.AdvanceSearchOptionTypeId Order by RN For XML Path ('')),1,1,'')
,'_0','')
,'_1','')
,'_2','')
,'_3','')
,'_4','')
From cte A
Group By AdvanceSearchOptionTypeId
Returns
AdvanceSearchOptionTypeId IDs
21 62
23 4,5,6,7,2

Answer 3

If interested in a helper function.
Tired of extracting strings (left, right, charindex, patindex, ...) I modified s split/parse function to accept TWO non-like delimiters. In this case a , and _.
Example
;with cte as (
Select A.AdvanceSearchOptionTypeId
,B.*
,RN = Row_Number() over(Order by (Select NULL))
From #AdvancedSearchSelectedDropdownName A
Cross Apply [dbo].[tvf-Str-Extract](','+A.SelectedIds,',','_') B
)
Select AdvanceSearchOptionTypeId
,IDs = stuff((Select ',' +RetVal From cte Where AdvanceSearchOptionTypeId=A.AdvanceSearchOptionTypeId Order by RN,RetVal For XML Path ('')),1,1,'')
From cte A
Group By AdvanceSearchOptionTypeId
Returns
AdvanceSearchOptionTypeId IDs
21 62
23 4,5,6,7,2
The TVF if Interested
CREATE FUNCTION [dbo].[tvf-Str-Extract] (#String varchar(max),#Delimiter1 varchar(100),#Delimiter2 varchar(100))
Returns Table
As
Return (
with cte1(N) As (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)),
cte2(N) As (Select Top (IsNull(DataLength(#String),0)) Row_Number() over (Order By (Select NULL)) From (Select N=1 From cte1 N1,cte1 N2,cte1 N3,cte1 N4,cte1 N5,cte1 N6) A ),
cte3(N) As (Select 1 Union All Select t.N+DataLength(#Delimiter1) From cte2 t Where Substring(#String,t.N,DataLength(#Delimiter1)) = #Delimiter1),
cte4(N,L) As (Select S.N,IsNull(NullIf(CharIndex(#Delimiter1,#String,s.N),0)-S.N,8000) From cte3 S)
Select RetSeq = Row_Number() over (Order By N)
,RetPos = N
,RetVal = left(RetVal,charindex(#Delimiter2,RetVal)-1)
From (
Select *,RetVal = Substring(#String, N, L)
From cte4
) A
Where charindex(#Delimiter2,RetVal)>1
)
/*
Max Length of String 1MM characters
Declare #String varchar(max) = 'Dear [[FirstName]] [[LastName]], ...'
Select * From [dbo].[tvf-Str-Extract] (#String,'[[',']]')
*/

Answer 4

Disclaimer.As per first Normal form, you should not store multiple values in a single cell. I would suggest you to avoid storing this way.
Still the approach would be: Create a UDF function which separates comma separated list into a table valued variable. Below code I have not tested. but, it gives idea on how to approach this problem.
Refer to CSV to table approaches
Declare #selectedIds varchar(max) = '';
SET #selectedIds = SELECT STUFF
(SELECT ','+ (SUBSTRING(c.value, 0, CHARINDEX('_', c.value, 0))
FROM #AdvancedSearchSelectedDropdownName AS tv
CROSS APPLY dbo.udfForCSVToList(SelectedIds) AS c
WHERE advanceSearchOptionTypeId = 23
FOR XML PATH('')),1,2,'');
SELECT #selectedIds