How to synchronize (to link , to match) data from the internal SQLite database with the MySQL database?

Question

I want to Match the student’s level and student’s class(SQFLite) with the student’s level and student’s class (MySQL)when fetching questions in MySQL.

I have an external MySQL database (localhost) that contains a "questions" table characterized by their level (Easy, Medium, Hard) and their class(1st class, 2nd class, 3rd class). I have an internal database (SQFLite) that contains a "students" table with level and class attributes that contain in the external MySQL database. I want to post only the questions that correspond to the level and class of the student that is already added in the internal database "SQFLite".

Problem: I posted all the questions in the JSON form but did not match the level and class of the student currently added.

Requirements: I want when I add a new student with their level and class in the internal database"SQFLite", the questions that are displayed must be matched to that of the student.

Try.php : get questions in json form

<?php
header("Content-type: application/json; charset=utf-8");
try{
$conn = new PDO('mysql:host=localhost;dbname=relations;charset=utf8','root','');
$conn ->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
}
catch(PDOException $exc){
    echo $exc->getMessage();
    die("could not connect");
}
?>

<?php
$makeQuery ="SELECT * FROM questions ";
$stamement = $conn-> prepare($makeQuery);
$stamement -> execute();
$myarray = array();
while ($resultsFrom = $stamement->fetch()){
    array_push(
        $myarray,array(
        "idques"=>intval($resultsFrom['idques']),
        "description"=>$resultsFrom['description'] 
        )
    );
}
echo json_encode($myarray);
?>

model.dart: contains the student's model

class Student {
  int _id;
  String _name;
  String _level;
  String _classes ;
  String _date;

  Student(this._name, this._level, this._classes, this._date);
  Student.withId(this._id, this._name, this._level, this._classes ,this._date);

  String get date => _date;
  String get level => _level;
  String get classes => _classes;
  String get name => _name;
  int get id => _id;

  set date(String value) {
    _date = value;
  }
  set level(String value) {
      _level = value;
  }
  set classes(String value) {
    _classes = value;
  }
  set name(String value) {
    if (value.length <= 255) {
      _name = value;
    }
  }

  Map<String, dynamic> toMap() {
    var map = Map<String, dynamic>();
    map["id"] = this._id;
    map["name"] = this._name;
    map["level"] = this._level;
    map["classes"] = this._classes;
    map["date"] = this._date;
    return map;
  }

  Student.getMap(Map<String, dynamic> map){
    this._id = map["id"];
    this._name = map["name"];
    this._level = map["level"];
    this._classes= map["classes"];
    this._date = map["date"];
  }
}

sql_helper.dart: contains the internal database(SQFLite)

import 'package:sqflite/sqflite.dart';
import 'dart:async';
import 'dart:io';
import 'model.dart';
import 'package:path_provider/path_provider.dart';

class SQL_Helper {
  static SQL_Helper dbHelper;
  static Database _database;

  SQL_Helper._createInstance();
  factory SQL_Helper() {
    if (dbHelper == null) {
      dbHelper = SQL_Helper._createInstance();
    }
    return dbHelper;
  }

  String tableName = "students_table";
  String _id = "id";
  String __name = "name";
  String __level= "level";
  String __classes = "classes";
  String __date = "date";

  Future<Database> get database async {
    if (_database == null){
      _database = await initializedDatabase();
    }
    return _database;
  }

  Future<Database> initializedDatabase() async {
    Directory directory = await getApplicationDocumentsDirectory();
    String path = directory.path + "students.db";
    var studentDB = await openDatabase(path, version: 1, onCreate: createDatabase);
    return studentDB;
  }

  void createDatabase(Database db, int version) async {
    await db.execute(
        "CREATE TABLE $tableName($_id INTEGER PRIMARY KEY AUTOINCREMENT, $__name TEXT, $__level TEXT,$__classes TEXT, $__date TEXT )");
  }

  Future<List<Map<String, dynamic>>> getStudentMapList() async {
    Database db = await this.database;
    var result = await db.query(tableName, orderBy: "$_id ASC");
    return result;
  }

  Future<int> insertStudent(Student student) async {
    Database db = await this.database;
    var result = await db.insert(tableName, student.toMap());
    return result;
  }

  Future<int> updateStudent(Student student) async{
    Database db = await this.database;
    var result = await db.update(tableName, student.toMap(), where: "$_id = ?", whereArgs: [student.id]);
    return result;
  }

  Future<int> deleteStudent(int id) async {
    var db = await this.database;
    int result = await db.rawDelete("DELETE FROM $tableName WHERE $_id = $id");
    return result;
  }

  Future<int> getCount() async {
    Database db = await this.database;
    List<Map<String, dynamic>> all = await db.rawQuery("SELECT COUNT (*) FROM $tableName");
    int result = Sqflite.firstIntValue(all);
    return result;
  }

  Future<List<Student>> getStudentList() async{
    var studentMapList = await getStudentMapList();
    int count = studentMapList.length;
    List<Student> students = new List<Student>();
    for (int i = 0; i <= count -1; i++){
      students.add(Student.getMap(studentMapList[i]));
    }
    return students;
  }
}

question.dart: contains questions list

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';

class Questions extends StatefulWidget {
  @override
  _QuestionsState createState() => _QuestionsState();
}

class _QuestionsState extends State<Questions> {
  getMethod()async{
    String theUrl = 'http://10.0.2.2/Try/Try.php';
    var res = await http.get(Uri.encodeFull(theUrl),headers:{"Accept":"application/json"});
    var responsBody = json.decode(res.body);
    print(responsBody);
    return responsBody;
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: new AppBar(
        title:Text("Questions", style: TextStyle(fontWeight: FontWeight.bold),) ,
        backgroundColor: Colors.blue[700],
      ),
      backgroundColor: Colors.blue[99],
      body:FutureBuilder(
        future: getMethod(),
        builder: (BuildContext context , AsyncSnapshot snapshot){
          List snap = snapshot.data;
          if(snapshot.connectionState == ConnectionState.waiting){
            return Center(
              child: CircularProgressIndicator(),
            );
          }
          if(snapshot.hasError){
            return Center(
              child: Text("Error .... "),
            );
          }
          return ListView.separated(
            separatorBuilder: (context, index) => Divider(
              color: Colors.indigo,
            ),
            itemCount: snap.length,
            itemBuilder: (context,index){
              return ListTile(
                title: Text(
                    "${snap[index]['description']}", style: TextStyle(fontSize: 18.0)),
                leading:Icon(Icons.question_answer, color:Colors.green , size: 20, ) ,
              );
            },
          );
        },
      ),
    );
  }
}