How to Retrieve from Checkbox Form Result with Adding [ in PHP?

For example I have Checkbox Form Result in MySQL like this: resultA, resultB, resultC, resultD, resultE

Now, I want to retrieve the results to be [resultA] [resultB] [resultC] [resultD] [resultE]

I have tried by EXPLODE and FOREACH but its result not so perfect. Is anybody can help me how to make it as I want?