Concatenate Multiple Rows From Multiple Tables

I've reviewed many other posts on here and have become pretty familiar with the Coalesce function, but I haven't been able to figure out how to do this specific task. So, I have a

Solution 1:

Thank you for the gist! So much better than pulling teeth to get schema and data. :-) If you plug this in to your gist query you should see the results you're after (well, very close - see below).

DECLARE @SalesRepID INT, @SurgeonID INT, @LocationID INT;
SELECT @SalesRepID = 2, @SurgeonID = 1, @LocationID = 1;

;WITH x AS 
(
  SELECT CommissionPercent, Categories = STUFF((SELECT ', ' 
      + tCat.Category FROM #tCategories AS tCat 
      INNER JOIN #tCommissions AS tCom 
      ON tCat.CategoryID = tCom.CategoryID
      WHERE tCom.CommissionPercent = com.CommissionPercent
      FOR XML PATH, TYPE).value('.', 'NVARCHAR(MAX)'), 1, 2, '') 
 FROM #tCommissions AS com
 WHERE SalesRepID = @SalesRepID
 AND SurgeonID = @SurgeonID
 AND LocationID = @LocationID
),
y AS
(
  SELECT s = RTRIM(CommissionPercent) + ' (' + Categories + ')' 
  FROM x GROUP BY CommissionPercent, Categories
)
SELECT Result = STUFF((SELECT ', ' + s FROM y 
  FOR XML PATH, TYPE).value('.', 'NVARCHAR(MAX)'), 1, 2, '');

The result is slightly different than you asked for, but you could fix that by applying string formatting when pulling CommissionPercent.

Result
--------------------------------------------------------
0.05 (Shirts, Shoes, Dresses), 0.10 (Hats), 0.15 (Pants)

Solution 2:

I bumped into similar problem before - and the only way I could resolve this (without using cursors), is by creating a CLR aggregate function. Here's an example in C# (and in VB): http://technet.microsoft.com/en-us/library/ms131056(v=SQL.90).aspx

I believe it just does what you need: concatenation.

Combining your example and the CLR, to achieve what you want - the SQL would look like:

SELECT
  c.CommissionPercent
  , dbo.MyAgg(cat.Category)
FROM #tCommissions AS c
JOIN #tCategories AS cat ON c.CategoryID = cat.CategoryID
group by c.CommissionPercent