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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，这将删除数据库中的会话。问题是，如果我单击删除按钮，则会出现未定义的索引错误，说明sessionsDrop第 200 行未定义我的问题是：

1：如何摆脱下面代码中的未定义索引错误 2：如何以及在哪里编写 if 语句，以便如果删除成功，它将回显“会话 ... 已删除”，否则如果没有t被删除然后显示回显“发生错误，会话...未删除”

下面是代码：

$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";
}
}
    ?>
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1 回答 1

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

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

因此，您应该使用$_REQUEST['session']=='', 而不是$_REQUEST['sessionsDrop']==''因为超级全局变量（$_POST, $_GET, $_REQUEST）引用的是name，而不是id.

于 2012-10-19T05:09:42.393 回答