从 sql 数据库中以 flutter datewise 方式获取数据？

Question

我正在 flutter 中制作一个应用程序，我正在使用 sqflite 插件实现 SQL 数据库。在此应用中，用户可以通过填写下面的表格来创建交易然后用户可以验证他们的交易，他们还可以选择编辑交易以防他们犯了错误现在我想添加一个功能，通过该功能，他们可以在下面的屏幕上获得他们在特定月份完成的费用总和它显示为空，但它应该显示费用总和

我的查询代码是

Future getDataJan() async{
final db = await database;
sumJan=await db.rawQuery(
    'SELECT SUM(AMOUNT) FROM EXPENSES WHERE DATE(DATETIME) >= ? AND DATE(DATETIME) <= ?',
    [2021-01-01, 2021-01-31] ).then(Sqflite.firstIntValue);
print(sumJan);
finalJan=sumJan.toString();
}

数据库创建：

Future<Database> createDatabase() async {
String dbPath = await getDatabasesPath();

return await openDatabase(
  join(dbPath, 'expenseDB.db'),
  version: 1,
  onCreate: (Database database, int version) async {
    print("Creating expense table");

    await database.execute(
      "CREATE TABLE $TABLE_EXPENSES ("
      "$COLUMN_ID INTEGER PRIMARY KEY,"
      "$COLUMN_NAME TEXT,"
      "$COLUMN_AMOUNT INTEGER,"
      "$COLUMN_UNNECESSARYEXPENSES INTEGER,"
      "$COLUMN_CATEGORY TEXT,"
      "$COLUMN_DATETIME TEXT"
      ")",
    );
  },
);
}

映射数据库（我认为它因为映射时的字符串而不起作用）：

Map<String, dynamic> toMap() {
var map = <String, dynamic>{
  DatabaseProvider.COLUMN_NAME: name,
  DatabaseProvider.COLUMN_AMOUNT: amount,
  DatabaseProvider.COLUMN_UNNECESSARYEXPENSES: isUnnecessaryExpenses ? 1 : 0,
  DatabaseProvider.COLUMN_CATEGORY: category,
  DatabaseProvider.COLUMN_DATETIME: pickedDate,
};

if (id != null) {
  map[DatabaseProvider.COLUMN_ID] = id;
}

return map;
}

数据库条目：

编辑：这是我创建一个 Widget 以调用日期选择的代码：

  Widget DatePicker() {

   showDatePicker(context: context, initialDate: DateTime.now(), firstDate: DateTime.parse("2020-01-01 00:00:01Z"), lastDate: DateTime.now()
  ).then((value){
    if (value == null){
      return;
     }
     _dateTime = value;
     ////saving in string
     pickedDate = DateFormat('yyyy-MM-dd').format(_dateTime);
     });
   }

Problematic Dude 建议后给出的错误：

lib/db/database_provider.dart:111:59: Error: Expected ',' before this.
  'SELECT SUM(AMOUNT) FROM EXPENSES WHERE strftime('%m' , date(datetime)) ==   01').then(Sqflite.firstIntValue);
                                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^
    lib/db/database_provider.dart:111:58: Error: The getter 'm' isn't defined  for the class 'DatabaseProvider'.
    - 'DatabaseProvider' is from 'package:finance_manager/db /database_provider.dart' ('lib/db/database_provider.dart').
    Try correcting the name to the name of an existing getter, or defining a   getter or field named 'm'.
  'SELECT SUM(AMOUNT) FROM EXPENSES WHERE strftime('%m' , date(datetime)) == 01').then(Sqflite.firstIntValue);
                                                     ^
   lib/db/database_provider.dart:111:57: Error: The operator '%' isn't defined for the class 'String'.
   Try correcting the operator to an existing operator, or defining a '%' operator.
  'SELECT SUM(AMOUNT) FROM EXPENSES WHERE strftime('%m' , date(datetime)) ==   01').then(Sqflite.firstIntValue);
                                                    ^
  lib/db/database_provider.dart:111:59: Error: The argument type 'String' can't be assigned to the parameter type 'List<dynamic>'.
- 'List' is from 'dart:core'.
     'SELECT SUM(AMOUNT) FROM EXPENSES WHERE strftime('%m' , date(datetime)) == 01').then(Sqflite.firstIntValue);

更新

我在 android 工作室中使用数据库检查器打开了数据库，并尝试运行在其中执行以下查询：

SELECT SUM(AMOUNT) FROM EXPENSES

SELECT SUM(AMOUNT) FROM EXPENSES WHERE DATE(DATETIME) >= 2021-01-01 and  DATE(DATETIME) <= 2021-01-31

上面的查询工作得很好并且 returns 列数量的总和 ，但是一旦我运行第二个查询它给了我再次为 null，我想我以错误的方式保存日期。

请帮忙。

感谢您的回复

Answer 1

您的函数在日期前后缺少引号

Future getDataJan() async{
final db = await database;
sumJan=await db.rawQuery(
    'SELECT SUM(AMOUNT) FROM EXPENSES WHERE DATE(DATETIME) >= ? AND DATE(DATETIME) <= ?',
    ['2021-01-01', '2021-01-31'] ).then(Sqflite.firstIntValue);
print(sumJan);
finalJan=sumJan.toString();
}

从 sql 数据库中以 flutter datewise 方式获取数据？

Fetching data from sql databse in flutter datewise?

sql

flutter

android-sqlite

android-database

sqflite