我正在嘗試將數組值綁定到 php pdo 中的一個准備好的語句，但只有綁定的數組的第一個元素

Question

我想顯示一個時間表，下面是我懷疑錯誤所在的代碼片段。 其中的錯誤是綁定僅使用我命名為 class 的數組的第一個元素，盡管 class 數組中有兩個元素。 請誰能幫我弄清楚我哪里出錯了？

while($classes = $stmt->fetch(PDO::FETCH_ASSOC)){

       $showtimetable.= "{\"class\":\"";
       $showtimetable.= $classes["Form"].$classes["Label"];
       $showtimetable.= "\",\"subjects\":[";

      //iterate every class in different times to check if they are having a session in the timetable
           foreach($time as $times){

             $selectlessonquery="SELECT `staffnumber`, `subject` FROM `".$timetablename."` WHERE 
            `Form`=? AND `Label`=? AND daytime=?"; 
                 try{ 
                        //this variable contain the array of variable classes
                         echo $classes["Form"].$classes["Label"];
                        //this works fine with output of classes as 1E and IN
                     //on adding these code that will use the value in $classes  only 1E it binding 
                       in prepared statement
                           $stmt=$conn->prepare($selectlessonquery);
                           $stmt->bindParam(1,$classes["Form"]);
                           $stmt->bindParam(2,$classes["Label"]);
                           $stmt->bindParam(3,$times);
                           $stmt->execute();
                           while($subject = $stmt->fetch(PDO::FETCH_ASSOC)){
                               if(!$subject){
                                  //if no matching row then make the value to be empty string
                                   $showtimetable.= "{\"subject\":\"";
                                   $showtimetable.= " \"";
                                   $showtimetable.= " "."},";  
                               }else{
                                   $showtimetable.= "{\"subject\":\"";
                                   $showtimetable.= $subject["subject"]." ";
                                   $showtimetable.= $subject["staffnumber"]."\"},";
                               }  

                           }
                      }catch(Exception $e){

                          echo "error Ocuured ". $e->getMessage();

                      }
                 }

                  $showtimetable=rtrim($showtimetable,",");
                  $showtimetable.="]";
                 $showtimetable.="},";

             }
      echo $showtimetable
 //the output contains on data relevant to 1E and it isnt looping to the other value as expected

Answer 1

你必須這樣做。 因為第二個參數必須在bindParam()通過引用傳遞。

$table = 'users';
$sql = "INSERT INTO `{$table}` (username, password, name, age) VALUES(?, ?, ?, ?)";

$stmt = $pdo->prepare($sql);
$stmt->bindParam(1, $username);
$stmt->bindParam(2, $password);
$stmt->bindParam(3, $name);
$stmt->bindParam(4, $age);

$username = 'zill';
$password = '12345';
$name = 'zilanicse';
$age = 31;

// Executes the query
$stmt->execute();

Answer 2

問題是 if 在一段時間內的定位導致代碼意外停止，即使它旨在在沒有獲取行的情況下為主題提供默認值。 正確的方法是

      foreach($time as $times){
         $selectlessonquery="SELECT `staffnumber`, `subject` FROM `".$timetablename."` 
          WHERE `Form`=? AND `Label`=? AND daytime=?"; 
              try{ 

                   //this variable contain the array of variable classes
                   $subjects=$conn->prepare($selectlessonquery);
                   $subjects->bindParam(1,$classes["Form"]);
                   $subjects->bindParam(2,$classes["Label"]);
                   $subjects->bindParam(3,$times);
                   $subjects->execute();

                   if($subjects->rowCount()==0){
                       $showtimetable.= "{\"subject\":\"";
                       $showtimetable.= " \"";
                      $showtimetable.= " "."},";  
                  }else{
                    while($subject=$subjects->fetch(PDO::FETCH_ASSOC)){

                         $showtimetable.= "{\"subject\":\"";
                         $showtimetable.= $subject["subject"]." ";
                        $showtimetable.= $subject["staffnumber"]."\"},";
                   }  

               }

          }catch(Exception $e){

                echo "error Ocuured ". $e->getMessage();

          }
       }