背靠背准备语句中第二个准备语句的问题

Question

我正在尝试使以下准备好的语句起作用。我正在尝试建立一个论坛，我目前正在做的部分是从主题中获取帖子。

第一个查询有效，num rows 部分也有效。我能够看到 "Add Replay" 按钮。但是，一旦我进入第二个查询，它就开始变得有点粗糙，我无法弄清楚到底出了什么问题。我有以下错误..

Warning: mysqli::query() expects parameter 1 to be string, object given

这条线

if ($result2 = $con->query($stmt2)) {

我试图从我的第二个查询的准备行中删除 if 以提供帮助，但它什么也没做。

是什么破坏了它，如果是，我该如何解决。如果那不是什么错，那是什么？

$con = new mysqli("localhost", "", "", "");
if (mysqli_connect_errno()) {
    throw new Exception("Connect failed: %s\n", mysqli_connect_error());
    exit();
}
    /* activate reporting */
$driver = new mysqli_driver();
try {
    $cid = $_GET['cid'];
    $tid = $_GET['tid'];
    $userid = ( isset( $_SESSION['user'] ) ? $_SESSION['user'] : "" );
        echo $cid . "<br>";
        echo $tid;
    //Prepare
    if ($stmt = $con->prepare("SELECT * FROM forum_topics WHERE `category_id`=? AND `id`=? LIMIT 1")) {

        $stmt->bind_param("ii", $cid, $tid);
        $stmt->execute();
        $stmt->bind_result($topic_id, $category_id, $topic_title, $topic_creator, $topic_last_user, $topic_date, $topic_reply_date, $topic_views); 

        //var_dump($stmt);

        if (!$stmt) {
            throw new Exception($con->error);
        }
    }
    $stmt->store_result();
    $numrows = $stmt->num_rows;
    echo $numrows;


    if($numrows == 1){
        echo "<table width='100%'>";
        if ( $_SESSION['user'] ) { 
            echo "<tr><td colspan='2'><input type='submit' value='Add Reply' onclick=\"window.location = 
        'forum_post_reply.php?cid=".$cid."$tid=".$tid."'\"> <hr />";
        } else {
            echo "<tr><td colspan='2'><p>Please log in to add your reply</p><hr /></td></tr>";
        }
        }

        while ($row = $stmt->fetch()) {

            //Prepared SELECT stmt to get forum posts
            //if($stmt2 = $con->prepare("SELECT `id`, `category_id`, `topic_id`, `post_creator`, `post_content`, `post_date` FROM forum_posts WHERE `category_id`=? AND `topic_id`=?")) 
            $stmt2 = $con->prepare("SELECT `id`, `category_id`, `topic_id`, `post_creator`, `post_content`, `post_date` FROM forum_posts WHERE `category_id`=? AND `topic_id`=?");
        if($stmt2===false) {
        die();
        } else {
            //var_dump($stmt2);

                $stmt2->bind_param("ii", $cid, $tid);
                $stmt2->execute();
                $stmt2->store_result();
                $stmt2->bind_result($post_id, $post_category_id, $post_topic_id, $post_creator, $post_content, $post_date);
                //$result2 = $stmt2->get_result();
                if (!$stmt2) {
                throw new Exception($con->error);
                }
            }
        }
        if ($result2 = $con->query($stmt2)) {
            while ($row2 = $result2->fetch_assoc() ) {
                echo "<tr><td valign='top' style='border: 1px solid #000000;'>
                <div style='min-height: 125px;'>".$row['topic_title']."<br />
                by ".$row2['post_creator']." - " .$row2['post_date']. "<hr />" . $row2['post_content'] ."</div></td>
                <td width='200' valign='top' align='center' style='border: 1px solid #000000;'>User Info Here!</td></tr>
                <tr><td colspan='2'><hr /></td></tr>";
            }
        }   else {
            echo "<p>This topic does not exist.</p>";
            }
}
catch (Exception $e)
{
    echo "Error: " . $e->getMessage();
}

更新：当前代码-

    while ($row = $stmt->fetch()) {

        //Prepared SELECT stmt to get forum posts
        $stmt2 = $con->prepare("SELECT `id`, `category_id`, `topic_id`, `post_creator`, `post_content`, `post_date` FROM forum_posts WHERE `category_id`=? AND `topic_id`=?");
    if($stmt2===false) {
    die();
    } else {
        //var_dump($stmt2);

            $stmt2->bind_param("ii", $cid, $tid);
            $stmt2->execute();
            $stmt2->store_result();
            $stmt2->bind_result($post_id, $post_category_id, $post_topic_id, $post_creator, $post_content, $post_date);
            //$result2 = $stmt2->get_result();
            if (!$stmt2) {
            throw new Exception($con->error);
            }
        }
    }
    $num_rows2 = $stmt2->num_rows;
    echo $num_rows2;
    //if ($result2 = $con->query($stmt2)) {
    //if ($result2 = $con->query("SELECT `id`, `category_id`, `topic_id`, `post_creator`, `post_content`, `post_date` FROM forum_posts WHERE `category_id`=? AND `topic_id`=?")) {
    if($num_rows2) {
        //while ($row2 = $result2->fetch() ) {
        while($row2 = $stmt2->fetch()) {
            echo "<tr><td valign='top' style='border: 1px solid #000000;'>
            <div style='min-height: 125px;'>".$row['topic_title']."<br />
            by ".$row2['post_creator']." - " .$row2['post_date']. "<hr />" . $row2['post_content'] ."</div></td>
            <td width='200' valign='top' align='center' style='border: 1px solid #000000;'>User Info Here!</td></tr>
            <tr><td colspan='2'><hr /></td></tr>";
        }   
    }   else {
        echo "<p>This topic does not exist.</p>";
        }

Answer 1

替换：

while($row2 = $stmt2->fetch()) {

与：

while($stmt2->fetch()) {

然后使用以下方法访问值：

$post_id // not $row2['post_id']

bind_result() 函数直接设置这些变量，如 here 所述。

背靠背准备语句中第二个准备语句的问题

Issues with second prepared statement in back to back prepared statements

php

mysql

prepared-statement

while-loop