Beginning Microsoft SQL Server 2008 ... - S3 Tech Training

Chapter 11: Writing Scripts and Batches
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Technically speaking, we could do this with nested IF...ELSE statements, but:
❑ It would be much harder to read — especially if the rules were more complex.
❑ We would have to implement the code using a cursor (bad!) and examine each row one at
a time.
In short — yuck!
A CASE statement is going to make this process relatively easy. What’s more, we’re going to be able to
place our condition inline to our query and use it as part of a set operation — this almost always means
that we’re going to get much better performance than we would with a cursor.
Our marketing department has decided they would like to see what things would look like if we
increased prices by 10 percent, so we’ll plug a 10 percent markup into a CASE statement, and, together
with a little extra analysis, we’ll get the numbers we’re looking for:
USE AdventureWorks2008;
GO
/* I’m setting up some holding variables here. This way, if we get asked
** to run the query again with a slightly different value, we’ll only have
** to change it in one place.
*/
DECLARE @Markup money;
DECLARE @Multiplier money;
SELECT @Markup = .10; -- Change the markup here
SELECT @Multiplier = @Markup + 1; -- We want the end price, not the amount
-- of the increase, so add 1
/* Now execute things for our results. Note that we’re limiting things
** to the top 10 items for brevity -- in reality, we either wouldn’t do this
** at all, or we would have a more complex WHERE clause to limit the
** increase to a particular set of products
*/
SELECT TOP 10 ProductID, Name, ListPrice,
ListPrice * @Multiplier AS “Marked Up Price”, “New Price” =
CASE WHEN FLOOR(ListPrice * @Multiplier + .24)
> FLOOR(ListPrice * @Multiplier)
THEN FLOOR(ListPrice * @Multiplier) + .95
WHEN FLOOR(ListPrice * @Multiplier + .5) >
FLOOR(ListPrice * @Multiplier)
THEN FLOOR(ListPrice * @Multiplier) + .75
ELSE FLOOR(ListPrice * @Multiplier) + .49
END
FROM Production.Product
WHERE ProductID % 10 = 0 -- this is just to help the example
ORDER BY ProductID DESC;
The FLOOR function you see here is a pretty simple one — it takes the value supplied and rounds down
to the nearest integer.