What are the pros and cons to keeping SQL in Stored Procs versus Code [closed]

Question

I am not a fan of stored procedures

Stored Procedures are MORE maintainable because: * You don't have to recompile your C# app whenever you want to change some SQL

You'll end up recompiling it anyway when datatypes change, or you want to return an extra column, or whatever. The number of times you can 'transparently' change the SQL out from underneath your app is pretty small on the whole

• You end up reusing SQL code.

Programming languages, C# included, have this amazing thing, called a function. It means you can invoke the same block of code from multiple places! Amazing! You can then put the re-usable SQL code inside one of these, or if you want to get really high tech, you can use a library which does it for you. I believe they're called Object Relational Mappers, and are pretty common these days.

Code repetition is the worst thing you can do when you're trying to build a maintainable application!

Agreed, which is why storedprocs are a bad thing. It's much easier to refactor and decompose (break into smaller parts) code into functions than SQL into... blocks of SQL?

You have 4 webservers and a bunch of windows apps which use the same SQL code Now you realized there is a small problem with the SQl code so do you rather...... change the proc in 1 place or push the code to all the webservers, reinstall all the desktop apps(clickonce might help) on all the windows boxes

Why are your windows apps connecting directly to a central database? That seems like a HUGE security hole right there, and bottleneck as it rules out server-side caching. Shouldn't they be connecting via a web service or similar to your web servers?

So, push 1 new sproc, or 4 new webservers?

In this case it is easier to push one new sproc, but in my experience, 95% of 'pushed changes' affect the code and not the database. If you're pushing 20 things to the webservers that month, and 1 to the database, you hardly lose much if you instead push 21 things to the webservers, and zero to the database.

More easily code reviewed.

Can you explain how? I don't get this. Particularly seeing as the sprocs probably aren't in source control, and therefore can't be accessed via web-based SCM browsers and so on.

More cons:

Storedprocs live in the database, which appears to the outside world as a black box. Simple things like wanting to put them in source control becomes a nightmare.

There's also the issue of sheer effort. It might make sense to break everything down into a million tiers if you're trying to justify to your CEO why it just cost them 7 million dollars to build some forums, but otherwise creating a storedproc for every little thing is just extra donkeywork for no benefit.

This is being discussed on a few other threads here currently. I'm a consistent proponent of stored procedures, although some good arguments for Linq to Sql are being presented.

Embedding queries in your code couples you tightly to your data model. Stored procedures are a good form of contractual programming, meaning that a DBA has the freedom to alter the data model and the code in the procedure, so long as the contract represented by the stored procedure's inputs and outputs is maintained.

Tuning production databases can be extremely difficult when the queries are buried in the code and not in one central, easy to manage location.

[Edit] Here is another current discussion

In my opinion you can't vote for yes or no on this question. It totally depends on the design of your application.

I totally vote against the use of SPs in an 3-tier environment, where you have an application server in front. In this kind of environment your application server is there to run your business logic. If you additionally use SPs you start distributing your implementation of business logic all over your system and it will become very unclear who is responsible for what. Eventually you will end up with an application server that will basically do nothing but the following:

(Pseudocode)

Function createOrder(Order yourOrder) 
Begin
  Call SP_createOrder(yourOrder)
End

So in the end you have your middle tier running on this very cool 4 Server cluster each of them equipped with 16 CPUs and it will actually do nothing at all! What a waste!

If you have a fat gui client that directly connects to your DB or maybe even more applications it's a different story. In this situation SPs can serve as some sort of pseudo middle tier that decouples your application from the data model and offers a controllable access.

Advantages for in Code:

• Easier to maintain - don't need to run a SQL script to update queries
• Easier to port to another DB - no procs to port

Actually, I think you have that backwards. IMHO, SQL in code is pain to maintain because:

• you end up repeating yourself in related code blocks
• SQL isn't supported as a language in many IDE's so you have just a series of un-error checked strings performing tasks for you
• changes in a data type, table name or constraint are far more prevalent than swapping out an entire databases for a new one
• your level of difficulty increases as your query grows in complexity
• and testing an inline query requires building the project

Think of Stored Procs as methods you call from the database object - they are much easier to reuse, there is only one place to edit and in the event that you do change DB providers, the changes happen in your Stored Procs and not in your code.

That said, the performance gains of stored procs is minimal as Stu said before me and you can't put a break point in a stored procedure (yet).

CON

I find that doing lots of processing inside stored procedures would make your DB server a single point of inflexibility, when it comes to scaling your act.

However doing all that crunching in your program as opposed to the sql-server, might allow you to scale more if you have multiple servers that runs your code. Of-course this does not apply to stored procs that only does the normal fetch or update but to ones that perform more processing like looping over datasets.

PROS

1. Performance for what it may be worth (avoids query parsing by DB driver / plan recreation etc)
2. Data manipulation is not embedded in the C/C++/C# code which means I have less low level code to look through. SQL is less verbose and easier to look through when listed separately.
3. Due to the separation folks are able to find and reuse SQL code much easier.
4. Its easier to change things when schema changes - you just have to give the same output to the code and it will work just fine
5. Easier to port to a different database.
6. I can list individual permissions on my stored procedures and control access at that level too.
7. I can profile my data query/ persistence code separate from my data transformation code.
8. I can implement changeable conditions in my stored procedure and it would be easy to customize at a customer site.
9. It becomes easier to use some automated tools to convert my schema and statements together rather than when it is embedded inside my code where I would have to hunt them down.
10. Ensuring best practices for data access is easier when you have all your data access code inside a single file - I can check for queries that access the non performant table or that which uses a higher level of serialization or select *'s in the code etc.
11. It becomes easier to find schema changes / data manipulation logic changes when all of it is listed in one file.
12. It becomes easier to do search and replace edits on SQL when they are in the same place e.g. change / add transaction isolation statements for all stored procs.
13. I and the DBA guy find that having a separate SQL file is easier / convenient when the DBA has to review my SQL stuff.
14. Lastly you don't have to worry about SQL injection attacks because some lazy member of your team did not use parametrized queries when using embedded sqls.

The performance advantage for stored procedures is often negligable.

More advantages for stored procedures:

• Prevent reverse engineering (if created With Encryption, of course)
• Better centralization of database access
• Ability to change data model transparently (without having to deploy new clients); especially handy if multiple programs access the same data model