如何使用Kotlin从片段内部访问活动中的SQLite DB？

class MyDatabaseHelper(context: Context) : SQLiteOpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION) {
    override fun onCreate(db: SQLiteDatabase?) {
        // 创建数据库表结构
        val createTableQuery = "CREATE TABLE $TABLE_NAME ($COLUMN_ID INTEGER PRIMARY KEY, $COLUMN_NAME TEXT)"
        db?.execSQL(createTableQuery)
    }

    override fun onUpgrade(db: SQLiteDatabase?, oldVersion: Int, newVersion: Int) {
        // 升级数据库表结构
        val upgradeQuery = "DROP TABLE IF EXISTS $TABLE_NAME"
        db?.execSQL(upgradeQuery)
        onCreate(db)
    }
}

class MyActivity : AppCompatActivity() {
    private lateinit var dbHelper: MyDatabaseHelper

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        dbHelper = MyDatabaseHelper(this)
    }
}

class MyFragment : Fragment() {
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        activity?.let { activity ->
            val db = (activity as MyActivity).dbHelper.writableDatabase

            // 执行数据库操作，例如插入数据
            val contentValues = ContentValues().apply {
                put(COLUMN_ID, 1)
                put(COLUMN_NAME, "Example")
            }

            db.insert(TABLE_NAME, null, contentValues)

            // 关闭数据库连接
            db.close()
        }
    }
}