One does not simply move a built-in table. Pick your chairs wisely. Might want to think about ADA compliance while you're at it as well. 
Engineered joists are probably the only thing that are actually able to be bored like that without problems. Assuming the design work was properly done, of course. Don't try that with traditional joists.
You can put some pretty huge holes in the joist at mid-span, because the joist is basically an I-beam and the lowest area of stress is in the middle. Round holes distribute stress the best as well.
