Is a database the right choice for data storage for my C# application?

I am developing a C# application and want to be sure I choose the best choice for data storage that fits these specs.

The program can have a infinite amount of data, but that data will only be used by a single user that is using the application. Each time the application is closed, I need to save the data, and it needs to be loaded in when the application is started.

I have looked at databases, but am unsure as to which would be best suited for my needs. Also, I wonder if I need a database at all given the above specs, maybe I should just use a binary file/XML file implementing serialization and deserialization.

Point me in the right direction please!

Thanks, OC

EDIT: One important factor I forgot to include is the necessity to allow one user to save all the entries he/she entered and export it to an external file that can be easily shared between applications/users.

Solution

Without knowing more about what your specific application does, it's hard (for us) to say whether a database is the right choice. However, there are some rules of thumb that you can use to help steer your decision.

A database may be a good choice when:

The data may be used by multiple users.
When concurrent activity is possible that must be correctly stored.
When the data collected does not all need to be loaded into memory at once.
When you wish to be able to query or report on data in complex ways.
When you want to have transparency into the data being stored using standard tools.
When changes are mostly localized rather than requiring the entire datastore to be rebuilt.
When your data lends itself to a relational (rather than say a hierarchical representation).

A database may not be the best choice when:

You only service a single user.
There is little concurrent activity, and the entire data model must be recreated when saving changes.
When there will be very little data, and it will be loaded into memory all at once.
When you data is hierarchical or difficult to model relationally.
When your application is document-oriented, and documents (files) will be sent to other users.
When there is a significant amount of binary data interspersed in the data your storing.
When you want to avoid dependencies to third party tools or services.
When the structure of your data model is likely to change frequently.

These are all rules of thumb ... no single condition is going to dictate whether to use a database or not. You must examine all of the considerations, and decide whether using a database will give you sufficient benefit - or not.

In many environments, (such as iPhone, for example) there is a built-in database layer available directly on the platform. There are also tools (like NSCoreData) which help you overcome the Object-Relational Modeling (ORM) impedence mismatch. In such cases, it may make a lot of sense to use a database ever for very simple data storage.

There are also a number of open source data persistence layers (NHiberante, DB4O, and others) that help simplify using a database as a persistence store ... which, if you can use them, can shift the equation in favor of using a database.

A database can substantially simplify the development of your application when you need to support queries or search functionality. Relational databases support a query language (SQL), which moves the effort of identifying and retrieving results from the database much easier. Letting the database do the heavy lifting can be a significant time saver - as databases are specifically designed to perform query operations correctly and efficiently. However, this comes at the cost of a well-designed relational data structure - which you must create.

One significant consideration, is whether users will share the data that they create/consume using your application. If your application is more document oriented (think Word, Excel, Powerpoint), then a file-based serialization model may be more appropriate. If your application's data will not be shared - then a database may make sense.

Another significant factor is how open you want your data to be. Databases store information in well-defined structures (tables), and this makes it easier for you (and your users) to directly access and inspect the data. Storage formats like XML, also allow this, but to a somewhat lesser extent.