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

Despite being schema-bound, this one still comes back as being non-deterministic. That’s because this
function references a table that isn’t local to the function (a temporary table or table variable created
inside the function).
Under the heading of “one more thing,” it’s also worth noting that the PriceDifference function we
created at the same time as AveragePrice is also non-deterministic. For one thing, we didn’t make it
schema-bound, but, more important, it references AveragePrice — if you reference a non-deterministic
function, then the function you’re creating is non-deterministic by association.
Debugging User-Defined Functions
This actually works just the same as the sproc example we saw in Chapter 12.
Simply set up a script that calls your function, and begin stepping through the script (using the toolbar
icon, or pressing F11). You can then step right into your UDF.
.NET in a Database W orld
Chapter 13: User-Defined Functions
As we discussed in Chapter 12, the ability to use .NET assemblies in our stored procedures and functions
was added to SQL Server back in SQL Server 2005. Much as it does with sprocs, this has enormous
implications for functions.
Considering most who read this title will be beginners, it’s hard to fully relate the impact that .NET has
in our database world. The reality is that you won’t use it all that often, and yet, when you do, the effects
can be profound. Need to implement a complex formula for a special function? No problem. Need to
access external data sources such as credit card authorization companies and such things? No problem.
Need to access other complex data sources? No problem. In short, things we used to have to either skip
or perform extremely complex development to achieve (in some cases, it was all smoke and mirrors
before) suddenly become relatively straightforward.
What does this mean in terms of functions? Well, I already gave the example of implementing a complex
formula in a function. But now imagine something like external tabular data — let’s say representing a
.csv or some other data in a tabular fashion — very doable with a .NET assembly created as a function
in SQL Server.
.NET assemblies in SQL Server remain, however, something of an advanced concept, and one I’ll defer
to the Professional series title for SQL Server 2008. That said, it’s important to understand that the option
is available and consider it as something worth researching in that “Wow, I have no idea how we’re
going to do this!” situation.
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