When should I use stored procedures?

Question

When should I be using stored procedures instead of just writing the logic directly in my application? I\'d like to reap the benefits of stored procedures, but I\'d also lik

Answer 1

If you are talking business logic rather than just "Should I use sprocs in general" I would say you should put business logic in sprocs when you are carrying out large set based operations or any other time executing the logic would require a large number of calls to the db from the app.

Answer 2

Complicated database queries for me tend to end up as stored procs. Another thought to consider is that your database might be completely separate and distinct from the application. Lets say you run an Oracle DB and you essentially are building an API for other application developers at your organization to call into. You can hide the complicated stuff from them and provide a stored proc in its place.

A very simple example:

registerUser(username, password)

might end up running a few different queries (check if it exists, create entries in a preference table, etc) and you might want to encapsulate them.

Of course, different people will have different perspectives (a DBA versus a Programmer).

Answer 3

It can also be very useful as a matter of encapsulation and in the philosophy of DRY. For instance I use stored functions for calculations inside a table that I need for several queries inside the code. This way I use the better performance as well as the ensuring that the calculation is always done the same way.

I would not use it for higher functionality or logic the should be in the business logic layer of an architecture, but focused on the model layer, where the functionality is clearly focused on the database design and possible flexibility of changing the database design without breaking the API to the other layers.

Answer 4

This depends entirely on your environment. The answer to the question really isn't a coding problem, or even an analysis issue, but a business decision.

If your database supports just one application, and is reasonably tightly integrated with it, then it's better, for reasons of flexibility, to place your logic inside your application program. Under these circumstances handling the database simply as a plain data repository using common functionality looses you little and gains flexibility - with vendors, implementation, deployment and much else - and many of the purist arguments that the 'databases are for data' crowd make are demonstratively true.

On the other hand if your are handling a corporate database, which can generally be identified by having multiple access paths into it, then it is highly advisable to screw down the security as far as you can. At the very least all appropriate constraints should enabled, and if possible access to the data should be through views and procedures only. Whining programmers should be ignored in these cases as...

1. With a corporate database the asset is valuable and invalid data or actions can have business-threatening consequences. Your primary concern is safeguarding the business, not how convenient access is for your coders.
2. Such databases are by definition accessed by more than one application. You need to use the abstraction that stored procedures offer so the database can be changed when application A is upgraded and you don't have the resource to upgrade application B.
3. Similarly the encapsulation of business logic in SPs rather than in application code allows changes to such logic to be implemented across the business more easily and reliably than if such logic is embedded in application code. For example if a tax calculation changes it's less work, and more robust, if the calculation has to be changed in one SP than multiple applications. The rule of thumb here is that the business rule should be implemented at the closest point to the data where it is unique - so if you have a specialist application then the logic for that app can be implemented in that app, but logic more widely applicable to the business should be implemented in SPs.

Coders who dive into religious wars over the use or not of SPs generally have worked in only one environment or the other so they extrapolate their limited experience into a cast-iron position - which indeed will be perfectly defensible and correct in the context from which they come but misses the big picture. As always, you should make you decision on the needs of the business/customers/users and not on the which type of coding methodology you prefer.

Answer 5

Wow... I'm going to swim directly against the current here and say, "almost always". There are a laundry list of reasons - some/many of which I'm sure others would argue. But I've developed apps both with and without the use of stored procs as a data access layer, and it has been my experience that well written stored procedures make it so much easier to write your application. Then there's the well-documented performance and security benefits.

Answer 6

I agree that they should be used often and well.

The use case I think is extremely compelling and extremely useful is if you are taking in a lot of raw information that should be separated out into several tables, where the some of the data may have records that already exist and need to be connected by foreign key id, then you can just IF EXISTS checks and insert if it doesn't or return key if it does, which makes everything more uniform, succinct, and maintainable in the long run.

The only case where I would suggest against using them is if you are doing a lot of logic or number crunching between queries which is best done in the app server OR if you are working for a company where keeping all of the logic in the code is important for maintainability/understanding what is happening. If you have a git repository full of everything anyone would need and is easily understandable, that can be very valuable.