我對sql部分有困難

Question

我發佈了一個關於我的網站的代碼。在這段代碼中，我想更新數據庫中的行，如果用戶更改了網站表單上主題的名稱。除sql部分外，一切正常。我的意思是這裏的部​​分：「LIMIT 1 OFFSET'$ x'」這部分sql代碼由於某種原因並不好，但我不知道爲什麼。我在xampp phpmyadmin中測試過它，但它的工作原理錯了。

<?php 
$sql = "SELECT topicname, username, created, COUNT(commentid) 
FROM user, topic, comment 
WHERE topic.topicid = comment.whichtopic 
AND user.userid = topic.owner 
AND user.username = '" . $_SESSION['user_name '] . "' 
GROUP BY topicname "; 
$lekerdezes = mysql_query($sql); 
$num_rows = mysql_num_rows($lekerdezes); ?> 
<?php 
if (isset($_POST['delete'])) 
{ 
    if (!empty($_POST['forumnev'])) 
    { 
     for ($x = 0; $x < $num_rows; $x++) 
     { 
      foreach ($_POST['forumnev'] as $selected) 
      { 
       $seged = mysql_query("SELECT created FROM topic WHERE 
             created IN (SELECT created FROM user, topic, comment WHERE topic.topicid = comment.whichtopic 
             AND user.userid = topic.owner AND user.username = '" . $_SESSION['user_name '] . "' 
             GROUP BY topicname ORDER BY created) 
             LIMIT 1 OFFSET '$x'"); 
       if (!$seged) 
       { 
        echo mysql_error(); 
       } 
       $seged2 = mysql_fetch_array($seged); 
       $seged2 = $seged2[0]; 
       if (!$seged2) 
       { 
        echo mysql_error(); 
       } 
       $sql = mysql_query("UPDATE topic SET topicname = '$selected' WHERE created = '$seged2'"); 

      } 
     } 
     header("Location: topicedit.php"); 
    } 
} 
?> 

Answer 1

嘗試更新如下：（希望你的極限：1和offset：$ X）

$seged = mysql_query("SELECT created FROM topic WHERE created IN (SELECT created 
           FROM user,topic,comment 
           WHERE topic.topicid = comment.whichtopic 
           AND user.userid = topic.owner 
           AND user.username = '". $_SESSION['user_name'] ."' 
           GROUP BY topicname 
           ORDER BY created) 
           LIMIT $x, 1");