select查询不会执行，是我的语法错了吗？

Question

显然我有错误，因为这个查询不会执行，任何人都可以看到原因吗？

$username=username;

$mysqli = @new mysqli($localhost, $user, $pass, $database);
$sql = "SELECT * FROM player_log WHERE user = '$username'AND log_status=online";
$result = $mysqli->query($sql);

if ($result->num_rows > 0){
echo "its works";

}

Answer 1

多个问题见下面的修改代码

添加了调用mysqli的标准方法（$username之后的空格不是问题）

$username=username;

$mysqli = @new mysqli($localhost, $user, $pass, $database);
$sql = "SELECT * FROM player_log WHERE user = '$username'AND log_status='online' ";

if ($result = $mysqli->query($sql)){

    printf("Select returned %d rows.\n", $result->num_rows);

    /* free result set */
    $result->close();
    echo "its works";
}