这个问题在这里已经有答案了：

mysql\u fetch\u array（）/mysql\u fetch\u assoc（）/mysql\u fetch\u row（）/mysql\u num\u rows等…期望参数1是资源（31个答案）
两年前关门了。
请帮我纠正这个错误。当我试图查看收件箱消息时，它会通过错误
警告：mysqli\u num\u rows（）期望参数1是mysqli\u result，给定布尔值
因为它来自$req1 mysql查询。我认为这个小组有问题，但不确定。这是密码。

$req1 = mysqli_query($con, 'select m1.id, m1.title, m1.timestamp, count(m2.id) as reps, users.id as userid, users.username from pm as m1, pm as m2,users where ((m1.user1="'.$_SESSION['userid'].'" and m1.user1read="no" and users.id=m1.user2) or (m1.user2="'.$_SESSION['userid'].'" and m1.user2read="no" and users.id=m1.user1)) and m1.id2="1" and m2.id=m1.id group by m1.id order by m1.id desc');
$req2 = mysqli_query($con, 'select m1.id, m1.title, m1.timestamp, count(m2.id) as reps, users.id as userid, users.username from pm as m1, pm as m2,users where ((m1.user1="'.$_SESSION['userid'].'" and m1.user1read="yes" and users.id=m1.user2) or (m1.user2="'.$_SESSION['userid'].'" and m1.user2read="yes" and users.id=m1.user1)) and m1.id2="1" and m2.id=m1.id group by m1.id order by m1.id desc');
?>
This is the list of your messages:<br />
<a href="new_pm.php" class="link_new_pm">New PM</a><br />
<h3>Unread Messages(<?php echo intval(mysqli_num_rows($req1)); ?>):</h3>