sql Flutter DatabaseHelper Class

import 'package:address_book/database/address_database.dart';
import 'package:address_book/database/db_conv.dart';
import 'package:path/path.dart';
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';

class DatabaseHelper {
  String dbName = 'addressbook.db';
  String tbName = 'books';
  final COLUMN_ID = 'id';
  final COLUMN_Name = 'name';
  final COLUMN_Address = 'address';
  final COLUMN_Phone = 'phone';
  final COLUMN_Viber = 'viber';
  final COLUMN_Facebook = 'facebook';
  final COLUMN_Mail = 'mail';
  final COLUMN_Image = 'image';
  final COLUMN_Serial = 'serial';
  final COLUMN_Roll = 'roll';

  static DatabaseHelper? databaseHelper;
  DatabaseHelper._create();
  Database? _database;

//Todo Check Database
  factory DatabaseHelper() {
    if (databaseHelper == null) {
      databaseHelper = DatabaseHelper._create();
    }
    return databaseHelper!;
  }
  Future<Database> getDatabase() async {
    if (_database == null) {
      _database = await initDatabase();
    }
    return _database!;
  }

  Future<Database> delSaveData(int? id) async {
    return _database!;
  }

//todo clear database
  Future<Database> clearAllData() async {
    return _database!;
  }

  Future<Database> initDatabase() async {
    // var directory = await getDatabasesPath();
    var directory = await getApplicationDocumentsDirectory();
    var db = join(directory.path, dbName);
    return openDatabase(db, version: 1, onCreate: _create);
  }

//Todo Id Del
  deleteData(int id) async {
    Database db = await delSaveData(id);
    return db.delete(tbName, where: 'id=?', whereArgs: [id]);
  }

//Todo create DataBase
  Future<void> _create(Database database, version) async {
    String sql =
        'CREATE TABLE $tbName($COLUMN_ID INTEGER PRIMARY KEY AUTOINCREMENT,$COLUMN_Name VARCHAR,$COLUMN_Address VARCHAR,$COLUMN_Phone VARCHAR,$COLUMN_Viber VARCHAR,$COLUMN_Facebook VARCHAR,$COLUMN_Mail VARCHAR,$COLUMN_Image VARCHAR,$COLUMN_Serial VARCHAR ,$COLUMN_Roll VARCHAR)';
    database.execute(sql);
  }

  //Todo Save

  Future<int> save(AddressDatabase addressDatabase) async {
    Database db = await getDatabase();
    return db.insert(tbName, addressDatabase.toMap());
  }

//Todo Get Data
  Future<List<AddressDatabase>> getStudantData() async {
    Database db = await getDatabase();
    var bookMap = await db.query(tbName);
    List<AddressDatabase> dataList =
        bookMap.map((e) => AddressDatabase.fromMap(e)).toList();
    return dataList;
  }

  //todo Db count
  Future<int> contactCount() async {
    Database db = await getDatabase();
    //var result = await db.query(tbName);
    var x = await db.rawQuery('SELECT COUNT (*) FROM $tbName');
    int? count = Sqflite.firstIntValue(x);
    print("DB ==> $count");
    return count!;
  }
}