warning problem: expects parameter 1 to be mysqli_result

mysqli_query() returns FALSE if there was an error in the query. So you should test for it...

/* Select queries return a resultset */
if ($result = mysqli_query($dbc, "SELECT Name FROM City LIMIT 10")) {
    printf("Select returned %d rows.\n", $result->num_rows);

    /* free result set */
    $result->close();
}

See this link for the mysqli_query reference http://php.net/manual/en/mysqli.query.php