php - Using volley to retrieve data(multiple rows) from mysql -

i'm creating quiz app , have retrive question display.this php , java code.i'll store data in array.i'm not able fetch data sql table.

 stringrequest stringrequest = new stringrequest(request.method.post,inserturl,             new response.listener<string>() {                 @override                 public void onresponse(string response) {                          try {                             jsonarray=new jsonarray(response);                             jsonobject jsonobject=jsonarray.getjsonobject(0);                             for(int k=0;k<jsonarray.length();k++)                             {                                 question[k]=jsonobject.getstring("question");                                 opta[k]=jsonobject.getstring("optiona");                                 optb[k]=jsonobject.getstring("optionb");                                 optc[k]=jsonobject.getstring("optionc");                                 optd[k]=jsonobject.getstring("optiond");                                 ans[k]=jsonobject.getstring("answers");                               }                         } catch (jsonexception e) {                             e.printstacktrace();                         }                  }             },             new response.errorlistener() {                 @override                 public void onerrorresponse(volleyerror error) {                     toast.maketext(quiz.this,error.tostring(),toast.length_long ).show();                 }             }){         @override         protected map<string, string> getparams() throws authfailureerror {             map<string,string> params = new hashmap<string,string>();             params.put(item_course,data);             return super.getparams();         }     };      requestqueue requestqueue = volley.newrequestqueue(this);     requestqueue.add(stringrequest);      

this php code

  <?php      require 'initquiz.php';    global $connect;   $response = array(); $course=$_post["course"]; $query = "select * questions course='$course'"; $result= mysqli_query($connect,$query) or die(mysqli_error($connect));  $response= array(); if (mysql_num_rows($result) > 0) {     while ($row = mysql_fetch_array($result)) {                $question = $row[0];                $optiona = $row[2];                   $optionb= $row[3];                      $optionc = $row[4];                      $optiond= $row[5];                                                   $answers= $row[6];                                           array_push($response,array("question"=>$question,"optiona"=>$optiona,"optionb"=>$optionb,"optionc"=>$optionc,"optiond"=>$optiond,"answers"=>$answers));            } } echo json_encode($response);   ?>   

issues code:

• you mixed mysql_* , mysqli_* extension
• your code vulnerable sql injection, use prepared statements
• your fetch simpler
• try avoid select *, instead select specific fields

---

try approach:

$response = []; if(isset( $_post["course"])){     $mysqli = new mysqli("host", "user", "password", "db");     if ($mysqli->connect_errno) {         printf("connect failed: %s\n", $mysqli->connect_error);         exit();     }      $query = "select * questions course = ?";     if ($stmt = $mysqli->prepare($query)) {         $stmt->bind_param("s",  $_post["course"]);         $stmt->execute();         while ($row = $stmt->fetch_assoc()) {             $response['data'][] = $row;         }         $response['success'] = true;     }     $mysqli->close(); }else{     $response['data'] = 'no course sent';     $response['success'] = false; } echo json_encode($response);