Multiple results for one field in a joined SQL query

Question

I'm not sure if this is possible from with a SQL query, but I'll give it a go.

I'm developing a SharePoint web part in C# that connects to a SQL database and runs a query, then databinds that result set to a gridview. It's working fine, but I have a small snag. For the most part, my query will return exactly one result for every field. I am displaying the information vertically, so it looks roughly like this:

Customer Name           Mr. Customer
Customer Address        980 Whatever St.
Customer City           Tallahassee

Everything displays fine. However, one of the tables in the database will pretty much always return multiple results. It lists different types of materials used for different products, so the schema is different because while each customer will obviously have one name, one address, one city, etc., they will all have at least one product, and that product will have at least one material. If I were to display that information on its own, it would look something like this:

Product              Steel Type              Wood Type             Paper Type
-----------------------------------------------------------------------------
Widget               Thick                   Oak                   Bond
Whatsit              Thin                    Birch
Thingamabob                                  Oak                   Cardstock

Ideally, I suppose the end result would be something like:

Customer Name           Mr. Customer
Customer Address        980 Whatever St.
Customer City           Tallahassee
Widget Steel            Thick
Widget Wood             Oak
Widget Paper            Bond
Whatsit Steel           Thin
Whatsit Wood            Birch
Thingamabob Wood        Oak
Thingamabob Paper       Cardstock

Another acceptable result could be something like the following, adding a few columns but only returning multiple results for those fields:

Customer Name        Mr. Customer
Customer Address     980 Whatever St.
Customer City        Tallahassee
Product              Steel Type              Wood Type             Paper Type
Widget               Thick                   Oak                   Bond
Whatsit              Thin                    Birch
Thingamabob                                  Oak                             

I'm open to any suggestions. I'd like to include this in the result set without a separate query, if that's possible. Here is the code that I am using to pull in the data:

                    SqlDataAdapter da = new SqlDataAdapter();
                    da.SelectCommand = cmd;
                    DataSet ds = new DataSet();
                    da.Fill(ds, "Specs");
                    DataSet flipped_ds = FlipDataSet(ds);
                    DataView dv = flipped_ds.Tables[0].DefaultView;
                    GridView outputGrid = new GridView();
                    outputGrid.ShowHeader = false;
                    outputGrid.DataSource = dv;
                    outputGrid.DataBind();
                    Controls.Add(outputGrid);

I would list my SQL query, but it's enormous. I'm pulling in well over one hundred fields right now, with lots of SUBSTRING formatting and concatenation, so it would be a waste of space, but it's really a fairly simple query where I'm selecting fields with the AS statement to get the names that I want, and using a few LEFT JOINs to pull in the data I need without several queries. The schema of the product/material table is something like this:

fldMachineID
fldProductType
fldSteel
fldWood
fldPaper

So obviously, each customer has a number of entries, one for each different fldProductType value. If I'm leaving anything out, I can add it. Thanks for everyone's time and help!

Answer 1

try this:

DECLARE @TableA  table (RowID int, Value1 varchar(5), Value2 varchar(5))
DECLARE @TableB  table (RowID int, TypeOf varchar(10))
INSERT INTO @TableA VALUES (1,'aaaaa','A')
INSERT INTO @TableA VALUES (2,'bbbbb','B')
INSERT INTO @TableA VALUES (3,'ccccc','C')
INSERT INTO @TableB VALUES (1,'wood')
INSERT INTO @TableB VALUES (2,'wood')
INSERT INTO @TableB VALUES (2,'steel')
INSERT INTO @TableB VALUES (2,'rock')
INSERT INTO @TableB VALUES (3,'plastic')
INSERT INTO @TableB VALUES (3,'paper')


;WITH Combined AS
(
SELECT
    a.RowID,a.Value1,a.Value2,b.TypeOf
    FROM @TableA                 a
        LEFT OUTER JOIN @TableB  b ON a.RowID=b.RowID

)
SELECT
    a.*,dt.CombinedValue
    FROM @TableA        a
        LEFT OUTER JOIN (SELECT
                             c1.RowID
                                 ,STUFF(
                                            (SELECT
                                                 ', ' + TypeOf
                                                 FROM Combined  c2
                                                 WHERE c2.rowid=c1.rowid
                                                 ORDER BY c1.RowID, TypeOf
                                                 FOR XML PATH('') 
                                            )
                                            ,1,2, ''
                                       ) AS CombinedValue
                             FROM Combined c1
                             GROUP BY RowID
                        ) dt ON a.RowID=dt.RowID

OUTPUT:

RowID       Value1 Value2 CombinedValue
----------- ------ ------ ------------------
1           aaaaa  A      wood
2           bbbbb  B      rock, steel, wood
3           ccccc  C      paper, plastic

Answer 2

"Flipping" dataset can be done in sql, for example see h@@p://stackoverflow.com/questions/2344590/how-do-i-transform-rows-into-columns-in-sql-server-2005 But I do agree that often times it's simpler to do this in C#

What KM suggested is expanded on in this article: http://www.simple-talk.com/sql/t-sql-programming/concatenating-row-values-in-transact-sql/