json_encode（）返回奇异值的对象数组

The below code has only array like ["a","b","c"] but returns [Object,Object,Object]. The result of which I need to use nested $each loop in ajax success function. Is there any better way to do it?

    if($_GET['semValue'])
    {
      $sem_value = $_GET['semValue'];
      try
      {  

         $stmt = $dbConn->prepare("SELECT Semester FROM CourseInfo");
         $semArray = array();
         if ($stmt->execute()) 
         {
           while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) 
           {
             $semArray[] = $row;
           }
         }
        echo json_encode($semArray);
        exit();

     }
    catch(PDOException $e)
    {
      echo 'Exception -> ';
      var_dump($e->getMessage());
    }

You're inserting entire row in main array so it will return multidimensional array instead of array of string.

To get the array of string replace the following lines.

while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) 
{
     $semArray[] = $row["Semester"];
}

Explanation:

$row would be like this,

$row= Array("semester"=>1);
$row= Array("semester"=>2);
// And so on

If you follow your current code then your final array would be like this,

$semArray = Array ( [0]=> Array("semester"=>1), [1]=> Array("semester"=>2));

So it becomes multidimensional array, that's why we use $row["Semester"] to make it single dimensional array of string/integer values.