As shadowfiend notes, fixtures are a common approach here.

However, you could also use a mock. What you're really testing here isn't the connection to the database or even that the database contains certain data, so you can rule that out of the equation. What you're testing is that some service (let's just say a 'method' for simplicity's sake) turns an input into an output in some particular way.

What you do, then, is mock the database connection for a particular test case so it returns a guaranteed result to whatever's doing the request in your method. You can then test that the method converts that input into the correct result. You've now unit tested the method rather than the entire service (in a nutshell - it can be more complex than that).