Theoretically this is a valid php statement that builds a valid sql statement, however, don't expect this code to do anything if you copy/paste it somewhere.
no, it is not correct.
I assume that ip, date and misc are non numeric type so you need to enclose them in ' character.
the correct synthax would be:
"INSERT INTO visitors (ip, date, misc)
VALUES('$ip','$date','$ip')";
