如何从Flutter SQFlite中获得特定的行计数？

Question

我使用flutter sqflite软件包创建了一个本地数据库，用于存储我的任务管理器应用程序 task 。现在，我想计算任务总数，并特别是完成任务的计数。

摘要：

我想向用户展示您完成了多少个任务以及在UI中必须执行更多任务。为此，我想要我提到的

特定

class Task implements Comparable {
  final int id;
  final String taskTitle;
  bool isDone;

  Task({
    required this.id,
    required this.taskTitle,
    required this.isDone,
  });

  Task.fromRow(Map<String, Object?> row)
      : id = row['id'] as int,
        taskTitle = row['taskTitle'] as String,
        isDone = (row['isDone'] as int) == 1 ? true : false;

  @override
  String toString() =>
      'Task:: id = $id , Title = $taskTitle , is Done = $isDone';

  @override
  int compareTo(covariant Task other) => other.id.compareTo(id);
}

计数

class TaskDatabase {
  final String dbName;
  Database? _db;

  List<Task> _tasksList = []; 

  final _streamController = StreamController<List<Task>>.broadcast();
  TaskDatabase({required this.dbName});

   Stream<List<Task>> all() =>
  _streamController.stream.map((tasks) => tasks..sort());

  // opening database function
  // closing database function
  // fetching database data function
  // deleting database data and updating etc...

}

。数据库并使用streamBuilder从该列表数据渲染UI。

示例数据库函数在数据库功能类中存在（OPEN DB FUNC）

Future<bool> open() async {
    if (_db != null) {
      return true;
    }

    final directory = await getApplicationDocumentsDirectory();
    final path = '${directory.path}/$dbName';

    try {
      final db = await openDatabase(path);
      _db = db;

      //creating the database table using sqflite
      const createTable = '''CREATE TABLE IF NOT EXISTS "TABLEOFTASKS" (
            "id"    INTEGER NOT NULL,
            "taskTitle" TEXT,
            "isDone"    INTEGER NOT NULL DEFAULT 0,
            PRIMARY KEY("id" AUTOINCREMENT));''';

      await db.execute(createTable);

      // read all existing task objects from the db

      _tasksList = await _fetchTasks();
      _streamController.add(_tasksList);
      return true;
    } catch (e) {
      print('error = $e');
      return false;
    }
  }

Answer 1

尝试使用它来获取所有任务的计数

var count = await database.rawQuery('SELECT COUNT(*) FROM TABLEOFTASKS');

，并使用它来完成所有完成任务，

var tasksDone = await database.rawQuery('SELECT COUNT(*), TABLEOFTASKS.isDone 
FROM TABLEOFTASKS WHERE TABLEOFTASKS.isDone = 1');

不确定它们是否在这种方式上工作，但是我在mySQL命令行中使用此查询，并且正常工作正常