I have a table with username and passwords that I want to input in Hotmail's username and password box. Is there a way to actually program this? Are you allowed to manipulate text boxes of someone else's webpage? Not for illegal purposes, just to make my job easier and to not have to input values manually one by one. Hotmail is just an example.
Yes, it is possible, but it's probably a very bad idea.
And finally; there are solutions that can already do this, although they don't use an SQL database. Look for form filler plugins; there's plenty of them for most major browsers, just pick one that suits your preferences.