Question

我想从下拉菜单中删除会话。用户将从下拉菜单中选择一个会话，然后单击删除按钮，然后应该删除数据库中的会话。问题是，如果我点击删除按钮，它会出现一个未定义的索引错误，表明{200}中未定义sessionsDrop我的问题是：

1：如何摆脱下面代码中未定义的索引错误 2：如何以及在何处编写if语句，以便在删除成功时，它将回显＆＃34;会话...被删除＆＃34;否则，如果它没有删除，则显示echo＆＃34;发生错误，会话...未被删除＆＃34;

以下是代码：

$sessionnum = 0;

 if (isset($_POST['modulesubmit'])) {

     if($_REQUEST['modulesDrop']==''){

         echo "Please Select a Module from the Drop Down Menu Above";

     }
     else{  

 var_dump($_POST['modulesDrop']);

        $sessionquery = "
             SELECT SessionId, SessionDate, SessionTime, ModuleId
             FROM Session
             WHERE
             (ModuleId = ?)
             ORDER BY SessionDate, SessionTime 
            ";

$sessionqrystmt=$mysqli->prepare($sessionquery);
// You only need to call bind_param once
$sessionqrystmt->bind_param("s",$_POST['modulesDrop']);
// get result and assign variables (prefix with db)

$sessionqrystmt->execute(); 

$sessionqrystmt->bind_result($dbSessionId,$dbSessionDate,$dbSessionTime, $dbModuleId);

 $sessionqrystmt->store_result();

$sessionnum = $sessionqrystmt->num_rows();   

    $dataArraySession = array();

 while ( $sessionqrystmt->fetch() ) { 

 $dataArraySession[$dbSessionId]['SessionDate'] = $dbSessionDate; 
 $dataArraySession[$dbSessionId]['SessionTime'] = $dbSessionTime;

}

   $sessionHTML = "";
   $sessionHTML .= '<select name="session" id="sessionsDrop">'.PHP_EOL;
   $sessionHTML .= '<option value="">Please Select</option>'.PHP_EOL;     

foreach ($dataArraySession as $sessionId => $sessionData) {

   $sessionHTML .= "<option value='$sessionId'>" . $sessionId . " - " . $sessionData['SessionDate']. " - " . $sessionData['SessionTime'] ."</option>".PHP_EOL;        

        }

   $sessionHTML .= '</select>';
}
 if ($sessionnum > 0) {

 ?>

     <form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post">
     <p>Sessions: <?php echo $sessionHTML; ?><input id="sessionSubmit" type="submit" value="Delete" name="sessionsubmit" /></p>      
    </form>       

<?php

}
else {
 echo "<p>Sorry, You have No Sessions under this Module</p>";
}

}

 if (isset($_POST['sessionsubmit'])) {

     if($_REQUEST['sessionsDrop']==''){ //line 200 where undefined index occurs

         echo "Please Select a Session from the Drop Down Menu Above to Delete a Session";

     }
     else{  

 var_dump($_POST['sessionsDrop']);

 $sessiondel = $_POST['sessionsDrop'];

         $sessiondeletesql = " DELETE sess 
        FROM Session AS sess 
        WHERE sess.SessionId = ?"; 


                if (!$delete = $mysqli->prepare($sessiondeletesql)) {
      // Handle errors with prepare operation here
    }

    //Dont pass data directly to bind_param store it in a variable
$delete->bind_param("s", $sessiondel);

 $delete->execute();

        if ($delete->errno) {
          // Handle query error here
        }

        $delete->close();

        echo "Session $sessiondel was Deleted";
}
}
    ?>

Answer 1

您的undefined index错误是因为您使用的是$_REQUEST['sessionsDrop']==''，但您的表单代码是 -

$sessionHTML .= '<select name="session" id="sessionsDrop">'.PHP_EOL;

所以你应该使用$_REQUEST['session']==''而不是$_REQUEST['sessionsDrop']==''，因为超级全局（$_POST，$_GET，$_REQUEST）引用了name ，而不是id。

尝试从下拉菜单中删除会话时发生未定义的索引错误

1 个答案: