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

If we create our sproc with this option, then the sproc will be recompiled each time that it runs, regardless
of other options chosen at runtime.
Extended Stored Procedures (XPs)
The advent of .NET in SQL Server has really changed the area of Extended Stored Procedures. These
used to be the bread and butter of the hard-core code scenarios — when you hit those times where basic
T-SQL and the other features of SQL Server just wouldn’t give you what you needed.
With the availability of .NET to deal with things like O/S file access and other external communication
or complex formulas, the day of the XP would seem to be waning. XPs still have their place in the world
for few reasons:
❑ Times where performance is so critical that you want the code running genuinely in process to
SQL Server (this is truly a radical approach in the .NET era)
❑ Situations where your administrators will not allow .NET code to execute for security reasons
(though allowing XPs, but not .NET, is somewhat silly if you ask me …)
For purposes of this book, I’ll merely say that SQL Server does allow for the idea of externally written
code that runs as a .DLL in process with SQL Server. XPs are created using C or C++.
A Brief Look at Recur sion
Recursion is one of those things that isn’t used very often in programming. Still, it’s also one of those
things for which, when you need it, there never seems to be anything else that will quite do the trick. As
a “just in case,” a brief review of what recursion is seems in order.
The brief version is that recursion is the situation where a piece of code calls itself. The dangers here
should be fairly self-evident — if it calls itself once, then what’s to keep it from calling itself over and
over again? The answer to that is you. That is, you need to make sure that if your code is going to be
called recursively, you provide a recursion check to make sure you bail out when it’s appropriate.
I’d love to say that the example I’m going to use is all neat and original — but it isn’t. Indeed, for an example,
I’m going to use the classic recursion example that’s used with about every textbook recursion discussion
I’ve ever seen — please accept my apologies now. It’s just that it’s an example that can be understood by
just about anyone, so here we go.
So what is that classic example? Factorials. For those who have had a while since math class (or their last
recursion discussion), a factorial is the value you get when you take a number and multiply it successively
by that number less one, then the next value less one, and so on, until you get to one. For example, the
factorial of 5 is 120 — that’s 5*4*3*2*1.
So, let’s look at an implementation of such a recursive sproc:
CREATE PROC spFactorial
@ValueIn int,
Chapter 12: Stored Procedures
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