php - 无法修复 PDO 建立动态 sql 时参数编号无效

Question

我一直在尝试修复以下 PDO 代码上的无效参数号，但没有成功。我已将范围缩小到 $tid 中生成动态字段和参数的两个 foreach 循环，因为代码在注释掉与 $tid 相关的所有部分时有效。但是，从输出的外观来看，我仍然无法弄清楚循环出了什么问题。谁能看出问题出在哪里吗？

PDO代码:

   try 
   {
      $comma = "";
      $tno = "";
      $c = "1";
      foreach($tid as $t)   
      { 

        $tno .= "{$comma}tno_{$c}";
        $tno_sql .= "{$comma}(SELECT tno from `model` WHERE model_no = :model_no{$c})";
        $tno_update .= "{$comma}tno_{$c} = :model_no1{$c}";
        $c++;
        $comma = ",";
      }

      $dbh = new PDO("mysql:host=$hostname;dbname=$databasename", $username, $password);
      $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

      $sql = "

     INSERT INTO `aid` (user_id,$tno,content,title,budget_min,budget_max,style) 
     VALUES (
             (SELECT id from `users` WHERE user_id = :user_id1),
              $tno_sql,:content1,:title1,:budget_min1,:budget_max1,:style1)
     ON DUPLICATE KEY UPDATE 
            $tno_update,content = :content2, title = :title2,budget_min = :budget_min2,
            budget_max  = :budget_max2,style = :style2
            ";
            $users = $dbh->prepare($sql);
            $users->bindValue(':user_id1',$_SESSION["user_id"]);

            $users->bindValue(':content1', $content);
            $users->bindValue(':content2', $content);

            $users->bindValue(':style1', $style);
            $users->bindValue(':style2', $style);

            $users->bindValue(':budget_min1', $budget_min);
            $users->bindValue(':budget_min2', $budget_min);

            $users->bindValue(':budget_max1',$budget_max);
            $users->bindValue(':budget_max2', $budget_max);

            $users->bindValue(':title1', $title);
            $users->bindValue(':title2', $title);

            $i = 1;         
            foreach ($tid as $t) { 
              $users->bindValue(':model_no{$i}', $t);
              $users->bindValue(':model_no1{$i}', $t);  
              print "':model_no{$i}',";
              print "':model_no1{$i}',";

              $i++;

            }

           $users->execute();
           $dbh = null;
   }

Answer 1

改变

  $users->bindValue(':model_no{$i}', $t);
  $users->bindValue(':model_no1{$i}', $t); 

至

  $users->bindValue(":model_no$i", $t);
  $users->bindValue(":model_no1$i", $t); 

字符串插值仅在值位于双引号内时发生。