T-SQL: For Loop, Temporary (in-memory) Tables and Stored Procedures

Question

I have a database structure like so:

SELECT * FROM Culture;
------------------------
Id  ShortName   FullName                Supported
22  en-US       English (United States) 1
23  fr-FR       French (France)         1
24  hi-IN       Hindi (India)           0

SELECT * FROM ResourceKey;
----------------------------
Id      Name
20572   HowAreYou
20571   Hello


SELECT * FROM Strings;
-----------------------
Id      CultureId   ResourceKeyId           ResourceValue
41133   22          20571                   Hello
41134   22          20572                   How are you?
41135   23          20571                   Bonjour
41136   23          20572                   Comment allez-vous?


SELECT * FROM Category;
------------------------
Id  Name
1   JavaScript


SELECT * FROM StringCategory;
------------------------------
Id  ResourceKeyId   CategoryId
1   20571           1
2   20572           1

I want a SQL query to give me the following results:

Key         CategoryName    en-US               fr-FR                   another-SupportedCulture                        And so on
-------------------------------------------------------------------------------------------------------------------------------------------------------------
Hello       JavaScript      Hello               Bonjour                 Value of hello in that supported culture        and so on for all supported cultures
HowAreYou   JavaScript      How are you?        Comment allez-vous?     Value of HowAreYou in that supported culture    and so on for all supported cultures

I know how to write a query for an individual culture. I figure I'll write individual queries for all cultures in the Culture table that have the Supported field set to 1 (true). Then, I'll apply a LEFT OUTER JOIN between the English culture (which will have all values) and all other cultures to get the above data set.

So far, I've gotten this far in writing the query for a single culture:

SELECT 
ResourceKey.Id AS ResourceKeyId, 
ResourceKey.Name AS [Key], 
Category.Name AS CategoryName, 
Culture.Id AS CultureId, 
Culture.ShortName AS CultureShortName, 
Strings.ResourceValue
FROM 
ResourceKey LEFT OUTER JOIN Strings ON ResourceKey.Id = Strings.ResourceKeyId
INNER JOIN Culture ON Strings.CultureId = Culture.Id
LEFT OUTER JOIN StringCategory ON ResourceKey.Id = StringCategory.ResourceKeyId
LEFT OUTER JOIN Category ON StringCategory.CategoryId = Category.Id
WHERE Strings.CultureId = 23; -- this will be a T-SQL stored procedure parameter I understand

Which returns the following results:

ResourceKeyId   Key         CategoryName    CultureId   CultureShortName    ResourceValue
----------------------------------------------------------------------------------
20571           Hello       JavaScript      23          fr-FR               Bonjour
20572           HowAreYou   JavaScript      23          fr-FR               Comment allez-vous?

Thing is: I am not sure how to go about writing a loop in T-SQL and then storing these individual data sets in a temporary memory area (I believe there is a term for it, for some table type expressions that reside in-memory and only for the duration of the T-SQL batch, precisely for situations like mine) in the SQL process and then applying a join on them. That's where I need help.

Thank you for your patience in reading through my question and for helping.

I am using Microsoft SQL Server 2008 Express R2.

Answer 1

If you want dynamic number of columns, you have to use dynamic SQL:

declare @stmt nvarchar(max)

select @stmt =
    isnull(@stmt + ', ', '') +
    'max(case when s.CultureId = ' + cast(c.Id as nvarchar(max)) +
    ' then s.ResourceValue end) as ' + quotename(c.ShortName)
from Culture as c
where c.Supported = 1

select @stmt = '
    select
        rk.Name as [Key],
        c.Name as CategoryName, ' + @stmt + '
    from StringCategory as sc
        inner join Category as c on c.Id = sc.CategoryId
        inner join ResourceKey as rk on rk.Id = sc.ResourceKeyId
        inner join Strings as s on s.ResourceKeyId = rk.Id
    group by rk.Name, c.Name
'

exec sp_executesql @stmt = @stmt;

sql fiddle demo

Answer 2

I got to know from a colleague that I need to apply a PIVOT here. T-SQL and SQL Server 2005 and upwards support a PIVOT operation. Here are some links on why a PIVOT is useful in a situation like the one described above and how to make one:

http://blogs.msdn.com/b/spike/archive/2009/03/03/pivot-tables-in-sql-server-a-simple-sample.aspx

http://www.codeproject.com/Tips/500811/Simple-Way-To-Use-Pivot-In-SQL-Query