MySQL not deleting records [closed]

Answer 1

Learn basic PHP string syntax:

$sql = "DELETE FROM sv_info WHERE id='.$id.' LIMIT 1";
       ^--start of PHP string                       ^---end of PHP string

You're generating the literal query string

DELETE FROM sv_info WHERE id='.4.' LIMIT 1

Note how your bad attempt at PHP string concatenation actually became part of the query string. you're already IN a php string, so you can't execute PHP inside that string - PHP is not recursively embeddable/executable.

Either of these would work:

$sql = "DELETE FROM sv_info WHERE id='$id' LIMIT 1";
$sql = "DELETE FROM sv_info WHERE id='" . $id . "' LIMIT 1";

but of course, still leave you vulnerable to sql injection attacks.

Answer 2

Your SQL statement here:

$sql = "DELETE FROM sv_info WHERE id='4' LIMIT 1";

Is not using your variable $id at all. You are trying to delete id = 4 with every execution. If that ID doesn't exist, you are silently doing nothing.