I keep getting the error listed below but it only says line 1 what does this mean and how do I fix it?

Here is the error I keep getting?

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '1' at line 1

here is the code.

if (isset($_POST['info_submitted'])) { 

$user_id = '5';

    $mysqli = mysqli_connect("localhost", "root", "", "sitename");
    $dbc = mysqli_query($mysqli,"SELECT learned_skills.*, users_skills.* 
                                 FROM learned_skills 
                                 INNER JOIN users_skills ON learned_skills.id = users_skills.skill_id 
                                 WHERE user_id='$user_id'");



    $skill = $_POST['skill'];
    $experience = $_POST['experience'];
    $year = $_POST['year'];

            if (mysqli_num_rows($dbc) == 0) {
                    $mysqli = mysqli_connect("localhost", "root", "", "sitename");
                    $query1 = mysqli_query($mysqli,"INSERT INTO learned_skills (skill, experience, year) 
                                                 VALUES ('" . $skill . "', '" . $experience . "', '" . $year . "')");
            }


            if (!mysqli_query($mysqli, $query1)) {
                    print mysqli_error($mysqli);
                    return;
            }

            $mysqli = mysqli_connect("localhost", "root", "", "sitename");
            $dbc = mysqli_query($mysqli,"SELECT id 
                                         FROM learned_skills 
                                         WHERE id='" . $skill . "' 
                                         AND experience='" . $experience . "' 
                                         AND year='" . $year . "'");

                        if (!$dbc) {
                                print mysqli_error($mysqli);
                        }  else {
                                while($row = mysqli_fetch_array($dbc)){
                                        $id = $row["id"];
                                }
                        }


                        $query2 = "INSERT INTO users_skills (skill_id, user_id, date_created) VALUES ('$id', '$user_id', NOW())";

                        if (!mysqli_query($mysqli, $query2)) {
                                print mysqli_error($mysqli);
                                return;
                        }


            if ($dbc == TRUE) {
                    $dbc = mysqli_query($mysqli,"UPDATE learned_skills 
                                                 JOIN users_skills 
                                                 ON (users_skills.skill_id = learned_skills.id) 
                                                 SET skill = '$skill', experience = '$experience', year = '$year'");

                    echo '<p class="changes-saved">Your changes have been saved!</p>';
            }


            if (!$dbc) {
                    print mysqli_error($mysqli);
                    return;
            }

}