This kind of test could be good for testing a large set of data with relatively little tester effort if there is not much developer logic between the database and the display to the end user. Our team has done this on a number of occasions, and it is especially useful for running large quantities of real production data through our tests to be sure that actual scenarios are handled as expected. Do make sure you do at least a little fixed input testing for rare scenarios that might be especially likely to be handled differently in the DB and on the web page - null values, special characters, and other oddities.
Personally, I would call this "integration testing", since you are testing the integration of the DB and the web site, and not "functional testing". For "functional testing", I d probably want to make a mock of the datasource (e.g., the database) that will provide pre-written sets of data in the format you expect.
Having said that, if I had high confidence in the validity of the DB data and if the logic between the DB query and the web page display was very small and low-risk, I would probably not bother with the mock and would let the integration test cover the functionality as well. I don t know that testing the functionality and integration separately would be a big quality win in this case, and there are likely better things you could do with the available testing time. If there is a lot of logic around this data, you should probably test the integration separately from the functionality. Additional integration testing would probably include things like, "What if the database can t be reached?" and "What if the database is slow?".
While this technique will work with Ajax, make sure your testing tools will work with Ajax. Specifically, think about how you will capture the database query results and how you will gather the results displayed on the web page.
I m assuming that the validity of the data in the query is being tested elsewhere, since you mentioned that this was just one type of test in the test plan. I m also just discussing integration with the database and this report and not other features or components, and not other aspects of testing (performance, security. etc.), since that was the scope of your question.