Rows in their own columns depending on their value

Answer 1

SELECT 
 np.Id, 
 np.Description, 
 MIN(Case promotionalCode WHEN 'A' THEN Price ELSE NULL END) AS 'A',
 MIN(Case promotionalCode WHEN 'B' THEN Price ELSE NULL END) AS 'B',
 MIN(Case promotionalCode WHEN 'C' THEN Price ELSE NULL END) AS 'C'
FROM 
 Price AS p 
INNER JOIN nProduct AS np ON p.nProduct = np.Id
GROUP BY 
 np.Id,
 np.Description

---

Here is a simple test example:

DECLARE @temp TABLE (
 id INT,
 description varchar(50),
 promotionalCode char(1),
 Price smallmoney
)

INSERT INTO @temp
select 1, 'Product 1', 'A', 5
 union
SELECT 1, 'Product 1',  'B', 4
 union
SELECT 1, 'Product 1', 'C', 2



SELECT
 id,
 description,
 MIN(Case promotionalCode WHEN 'A' THEN Price ELSE NULL END) AS 'A',
 MIN(Case promotionalCode WHEN 'B' THEN Price ELSE NULL END) AS 'B',
 MIN(Case promotionalCode WHEN 'C' THEN Price ELSE NULL END) AS 'C'
FROM
  @temp
GROUP BY 
 id,
 description

Answer 2

Duckworth's answer is good. If you can get more than one value for each cell, you might want to use AVG or SUM instead of MIN, depending on what you want to see.

If your DBMS supports it, you might also want to look into a Crosstab query, or a pivot query. For example, MS Access has crosstab queries.

Answer 3

Here's a Q&A about how to transform rows into columns:
http://stackoverflow.com/questions/152770/transpose-a-set-of-rows-as-columns-in-sql-server-2000

Answer 4

If you're using SQL Server 2005, you can use the new PIVOT operator.

Simple PIVOT -- the number of orders a customer places for individual products.

Structure of a simple Order table:

CREATE TABLE Sales.[Order]
    (Customer varchar(8), Product varchar(5), Quantity int)

The table contains the following values:

Customer Product Quantity
    Mike  Bike  3
    Mike  Chain  2
    Mike  Bike  5
    Lisa  Bike  3
    Lisa  Chain  3
    Lisa  Chain  4

Ex: a PIVOT operation on the Order table:

SELECT *
    FROM Sales.[Order]
    PIVOT (SUM(Quantity) FOR Product IN ([Bike],[Chain])) AS PVT

The expected output from this query is:

Customer Bike Chain
Lisa      3  7
Mike      8  2

If you aren't using SQL Server, you might search for "pivot" for your database.