在PHP中显示SQL查询的字符串结果

Question

我正在尝试显示一个结果，该结果将显示在给定时间跨度内支付的所有租金的总和。但是我收到了错误＆＃34;可恢复的致命错误：类mysqli_result的对象无法转换为字符串＆＃34;

有没有办法可以使用PHP显示这些数据？

以下是我的代码：

<?php
ini_set('display_errors', 1); ini_set('log_errors',1); error_reporting(E_ALL); mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);

  $dateto = filter_input(INPUT_POST, 'dateto');
  $datefrom = filter_input(INPUT_POST, 'datefrom');


  if(!empty($dateto)){
if(!empty($datefrom)){
$host = "";
$dbusername = "";
$dbpassword = "";
$dbname = "some_db";

//new connection
$conn = new mysqli ($host, $dbusername, $dbpassword, $dbname);

if(mysqli_connect_error()){
  die('Connect Error ('. mysqli_connect_errno().')'
  . mysqli_connect_error());
}
else{
  $sql = "SELECT SUM(rentpm) FROM tenants";

  $result = $conn->query($sql);



  if ($conn->query($sql)){
    echo $result;

  }
  else{
    echo "Error: " . $sql ."<br>".$conn->error;
  }
  $conn->close();
}

}
else{
  echo "All fields are required!";
  die();
}
  }
  else{
    echo "Please fill out all fields to continue.";
    die();
  }
?>