[Flutter]SQLite

加入套件

在pubspec.yaml添加sqflite與path_provider。

建立數據模型

• id：識別欄位，唯一值為整數資料類型
• name：存放名字為字串資料類型

class People {
  final int? id;
  final String? name;
  
  Student({this.id, this.name});

  Map<String, dynamic> toMap() {
    return {
      'id': id,
      'name': name,
    };
  }
}

建立資料庫接口

class DatabaseHelper {
  static final _databaseName = "your_database_name.db";
  static final _databaseVersion = 1;

  static final table = 'your_table';


  //Singleton 單例模式，確保一個類別只有一個實例
  DatabaseHelper._privateConstructor();

  static final DatabaseHelper instance = DatabaseHelper._privateConstructor();


  static Database? _database;

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

  _initDatabase() async {
    Directory documentsDirectory = await getApplicationDocumentsDirectory();
    String path = join(documentsDirectory.path, _databaseName);
    return await openDatabase(path,
        version: _databaseVersion, onCreate: _onCreate);
  }

  Future _onCreate(Database db, int version) async {
    await db.execute('''
          CREATE TABLE $table (
            id INTEGER PRIMARY KEY,
            name TEXT NOT NULL,
          )
          ''');
  }


  Future<int> insert(Map<String, dynamic> row) async {
    Database? db = await instance.database;
    return await db!.insert(table, row);
  }


  Future<List<Map<String, dynamic>>> queryAllRows() async {
    Database? db = await instance.database;
    return await db!.query(table);
  }


  Future<int?> queryRowCount() async {
    Database? db = await instance.database;
    return Sqflite.firstIntValue(
        await db!.rawQuery('SELECT COUNT(*) FROM $table'));
  }

  Future<int> update(Map<String, dynamic> row) async {
    Database? db = await instance.database;
    int id = row['id'];
    return await db!.update(table, row, where: 'id = ?', whereArgs: [id]);
  }

  Future<int> delete(int id) async {
    Database? db = await instance.database;
    return await db!.delete(table, where: 'id = ?', whereArgs: [id]);
  }
}