Best method to write a recursive SQL view - sql-server

Question

I am looking for the cleanest SQL query to attain the following. Performance is not as important because my dataset is small.
Sample table:
Letter field holding: A, B, C, D, E,
Location field holding: UAE, CANADA, BOSTON, BAHRAIN, FRANCE
And I am looking for a result that lists every letter/location with letter in it combination, so the following result set:
A-UAE
A-CANADA
A-BAHRAIN
A-FRANCE
B-BOSTON
B-BAHRAIN
C-CANADA
C-FRANCE
D-CANADA
E-UAE
E-FRANCE

Answer 1

This is yet another solution:
DECLARE #Letter TABLE (
letter CHAR(1) PRIMARY KEY
);
DECLARE #Country TABLE (
name VARCHAR(100) PRIMARY KEY
);
INSERT INTO #Letter (letter)
VALUES ('A'), ('B'), ('C'), ('D'), ('E');
INSERT INTO #Country (name)
VALUES ('UAE'), ('CANADA'), ('BOSTON'), ('BAHRAIN'), ('FRANCE');
SELECT CONCAT(L.letter, ' - ', C.name)
FROM #Letter AS L
INNER JOIN #Country AS C
ON C.name LIKE '%' + L.letter + '%'
ORDER BY L.letter, C.name;
Result:
A - BAHRAIN
A - CANADA
A - FRANCE
A - UAE
B - BAHRAIN
B - BOSTON
C - CANADA
C - FRANCE
D - CANADA
E - FRANCE
E - UAE
Hopefull this outputs what you'd expect.
You can run this query on Stack Exchange Data: https://data.stackexchange.com/stackoverflow/query/622821
Alternatively, if performance becomes issue, you could create a seperate table which would store each country name and its' unique letters, so you could make a simple join instead of LIKEing to compare things:
DECLARE #CountrySplit TABLE (
letter CHAR(1)
, name VARCHAR(100)
, PRIMARY KEY (letter, name)
);
INSERT INTO #CountrySplit (letter, name)
SELECT DISTINCT SUBSTRING(C.name, v.number + 1, 1), C.name
FROM #Country AS C
INNER JOIN master..spt_values AS V
ON V.number < LEN(C.name)
WHERE V.type = 'P';
SELECT CONCAT(L.letter, ' - ', CS.name) AS Result
FROM #CountrySplit AS CS
INNER JOIN #Letter AS L
ON L.letter = CS.letter;
This is query on Stack Exchange Data:
https://data.stackexchange.com/stackoverflow/query/622841
Credits to this answer for string split: T-SQL Split Word into characters

Answer 2

With the help of a Parse/Split UDF and a Cross Apply.
I added an ID to demonstrate that this can be run for the entire table
Example
Declare #YourTable table (ID int,Letter varchar(50),Location varchar(50))
Insert Into #YourTable values
(1,'A, B, C, D, E,','UAE, CANADA, BOSTON, BAHRAIN, FRANCE')
Select A.ID
,B.*
From #YourTable A
Cross Apply (
Select NewValue = B1.RetVal+'-'+B2.RetVal
From [dbo].[udf-Str-Parse](A.Letter,',') B1
Join [dbo].[udf-Str-Parse](A.Location,',') B2
on charindex(B1.RetVal,B2.RetVal)>0
) B
Returns
ID NewValue
1 A-UAE
1 A-CANADA
1 A-BAHRAIN
1 A-FRANCE
1 B-BOSTON
1 B-BAHRAIN
1 C-CANADA
1 C-FRANCE
1 D-CANADA
1 E-UAE
1 E-FRANCE
The UDF if needed
CREATE FUNCTION [dbo].[udf-Str-Parse] (#String varchar(max),#Delimiter varchar(10))
Returns Table
As
Return (
Select RetSeq = Row_Number() over (Order By (Select null))
,RetVal = LTrim(RTrim(B.i.value('(./text())[1]', 'varchar(max)')))
From (Select x = Cast('<x>' + replace((Select replace(#String,#Delimiter,'§§Split§§') as [*] For XML Path('')),'§§Split§§','</x><x>')+'</x>' as xml).query('.')) as A
Cross Apply x.nodes('x') AS B(i)
);
--Thanks Shnugo for making this XML safe
--Select * from [dbo].[udf-Str-Parse]('Dog,Cat,House,Car',',')
--Select * from [dbo].[udf-Str-Parse]('John Cappelletti was here',' ')
--Select * from [dbo].[udf-Str-Parse]('this,is,<test>,for,< & >',',')
EDIT - Option without a UDF
Declare #YourTable table (ID int,Letter varchar(50),Location varchar(50))
Insert Into #YourTable values
(1,'A, B, C, D, E,','UAE, CANADA, BOSTON, BAHRAIN, FRANCE')
Select A.ID
,B.*
From #YourTable A
Cross Apply (
Select NewValue = B1.RetVal+'-'+B2.RetVal
From (
Select RetSeq = Row_Number() over (Order By (Select null))
,RetVal = LTrim(RTrim(B.i.value('(./text())[1]', 'varchar(max)')))
From (Select x = Cast('<x>' + replace((Select replace(A.Letter,',','§§Split§§') as [*] For XML Path('')),'§§Split§§','</x><x>')+'</x>' as xml).query('.')) as A
Cross Apply x.nodes('x') AS B(i)
) B1
Join (
Select RetSeq = Row_Number() over (Order By (Select null))
,RetVal = LTrim(RTrim(B.i.value('(./text())[1]', 'varchar(max)')))
From (Select x = Cast('<x>' + replace((Select replace(A.Location,',','§§Split§§') as [*] For XML Path('')),'§§Split§§','</x><x>')+'</x>' as xml).query('.')) as A
Cross Apply x.nodes('x') AS B(i)
) B2
on charindex(B1.RetVal,B2.RetVal)>0
) B