Question

如何从下拉列表PHP MySQL的选定选项中更新值：

因此，我尝试执行以下操作：单击提交按钮时，它将MySQL表中的set_default更新为1，这将成为测验，而默认测验将被其覆盖并设置其值到0。

        <form  method="POST" action="index.php">

        <select name="data">

        <?php echo $options;?>

    </select>


        <input type="submit" name="defaultQuiz" value="Set Quiz"   >
            </form>
 <?php

if(isset($_POST['defaultQuiz'])&& $_POST['defaultQuiz'] != ""){
    $defaultQ = $_POST['data'];
      require_once("scripts/connect_db.php");

    mysqli_query($db,"UPDATE quizes SET set_default=0 WHERE set_default=1")or 
    die(mysqli_error($db));
    mysqli_query($db,"UPDATE quizes SET set_default=1 WHERE quiz_name='$defaultQ'")or die(mysqli_error($db));


    $defaultQ_sql1 = mysqli_query($db,"SELECT id FROM quizes WHERE set_default=1")or die(mysqli_error($db));

    $numDefaults = mysqli_num_rows($defaultQ_sql1);

    if($numDefaults < 1 || $numDefaults > 1){
        echo "Sorry, there was a problem setting /".$defaultQ."/ default. Please try again later.";
        exit();
    }else{
        echo "Thanks! The quiz, /".$defaultQ."/ has now been set as default.";
        exit();
    }
}

但是，我总是收到错误消息“很抱歉，设置$ defaultQ.default ..时出现问题。我已经尝试过多次更改代码，但是我确定问题出在

mysqli_query($db,"UPDATE quizes SET set_default=0 WHERE set_default=1")
   or die(mysqli_error($db));
mysqli_query($db,"UPDATE quizes SET set_default=1 WHERE quiz_name='$defaultQ'")
   or die(mysqli_error($db));

功能

如何从下拉列表的选定选项中更新值？

0 个答案: