If you search through the suggestion forum, this comes up every 6 months or so.

What is the 'best answer'? One of the first rules about SQL is that there's seldom one best answer for all cases.

Who decides if a solution is correct? The person asking the question can't, if they knew what the correct answer was, they wouldn't be asking the question.

What happens when the OP follows some utterly dangerous advice without realising it, marks that very dangerous advice as 'The Correct Answer' then goes away (because he's happy) and a few hours later some other people come along to correct the advice, but the very dangerous solution remains marked as 'The Correct Answer'