更新和插入查询在php中不起作用

我现在被卡住了，因为我的更新和插入查询不工作，选择查询工作得很好

下面是我的代码

<?php 
    if(isset($_POST['save'])){
        $exam_type=$_POST['exam_type'];
        $exam_from=$_POST['exam_from'];
        $exam_to=$_POST['exam_to'];
        $total_points=$_POST['total_points'];
        $passing_grade=$_POST['passing_grade'];
        $time_limit=$_POST['hrs']*360 + $_POST['min']*60;
        $cid=$_GET['cid'];

        $sql = $con->prepare("UPDATE new_oes.exam"
        . " SET exam_type=?,exam_from =?, exam_to=?,"
        . "modified_by=?,passing_score=?, time_limit=?,passing_grade=? "
        . "WHERE exam_type = ? AND cid =? ");

        $sql->execute(array($exam_type, $exam_from, $exam_to, $username, 
        $total_points, $time_limit, $passing_grade, $exam_type,$cid)) or die(mysqli_error($con));

        // echo $result1;
        //  $this->query($sql);
        if(mysqli_affected_rows($con)>0){
            echo "<script type='text/javascript'>alert('Exam Updated!!!')</script>";
            exit;
        } else{ 
            echo "An error occurred, try again later!!!";
        }
    }
?>

---

似乎
$username
没有定义，您应该定义
$username

$username = "SOME_ONE"; // maybe you saved it in $_SESSION or its in $_POST

通常，在尝试执行查询之前，您需要检查尝试
准备
sql语句的返回值。我不确定执行调用是如何执行的，因为它将数组指定为参数，这在PDO中更为常见-我认为您应该在执行之前将参数绑定到占位符，如下所示：

<?php
    try{
        if( isset( 
            $_POST['save'],
            $_POST['exam_type'],
            $_POST['exam_from'],
            $_POST['exam_to'],
            $_POST['total_points'],
            $_POST['passing_grade'],
            $_POST['hrs'],
            $_GET['cid'],
            $_GET['username'])
        ){

            $exam_type=$_POST['exam_type'];
            $exam_from=$_POST['exam_from'];
            $exam_to=$_POST['exam_to'];
            $total_points=$_POST['total_points'];
            $passing_grade=$_POST['passing_grade'];
            $time_limit=$_POST['hrs']*360 + $_POST['min']*60;
            $cid=$_GET['cid'];
            $username=$_GET['username'];

            $stmt = $con->prepare("update `new_oes`.`exam`
                set `exam_type`=?, `exam_from` =?, `exam_to`=?, `modified_by`=?, `passing_score`=?, `time_limit`=?, `passing_grade`=?
                where `exam_type` = ? and `cid` =? ");

            if( $stmt ){
                /*
                    Assumed to be that all parameters are strings apart from $cid which I took to be an integer
                    Change each letter in first parameter of `bind_param` accoring to whether the input variable is
                    either string or numeric.

                    s=string
                    i=integer
                */

                $stmt->bind_param( 'ssssssssi', $exam_type, $exam_from, $exam_to, $username, $total_points, $time_limit, $passing_grade, $exam_type, $cid );
                $stmt->execute();

                if( $stmt->affected_rows > 0 ){
                    exit( "<script>alert('Exam Updated!!!')</script>" );
                } else{ 
                    throw new Exception('An error occurred, try again later!!!');
                }               

            } else { 
                throw new Exception('Failed to prepare SQL statement!');
            }
        } else {
            throw new Exception('Required variables are not yet set');
        }
    }catch( Exception $e ){
        echo $e->getMessage();
    }
?>

这是mysqli还是PDO？哪里设置了$username？@NigelRen$username来自会话，设置在该代码之前的某个位置。建议也将其设置到if语句中？此处没有插入提示！终于成功了！。我的html表单有问题。再次感谢