Chapter 21. Using Databases

Everything from web forums to podcatchers or even backup programs frequently use databases for persistent storage. SQL-based databases are often quite convenient: they are fast, can scale from tiny to massive sizes, can operate over the network, often help handle locking and transactions, and can even provide failover and redundancy improvements for applications. Databases come in many different shapes: the large commercial databases such as Oracle, open source engines such as PostgreSQL or MySQL, and even embeddable engines such as Sqlite.

Because databases are so important, Haskell support for them is important as well. In this chapter, we will introduce you to one of the Haskell frameworks for working with databases. We will also use this framework to begin building a podcast downloader, which we will further develop in Chapter 22.