self sqflite sample =======================

import 'package:path_provider/path_provider.dart';
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path/path.dart';
import 'package:rxdart/rxdart.dart';
 
main() =>runApp(MaterialApp(home: MyApp(),));
 
 
class MyApp extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return MyAppState();
  }
}
 
class MyAppState extends State<MyApp> {
  TextEditingController _textController = TextEditingController();
 
  Future createDB() async{
    var path =(await getApplicationDocumentsDirectory()).path;
    var dbPath = join(path, 'whois.db');
    Database _database = await openDatabase(dbPath, version: 1, onCreate: (db, ver){
      db.execute('CREATE TABLE whois (id INTEGER PRIMARY KEY, name TEXT)');
    });
    return _database;
  }
//mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
  Future addData (String table, Map<String, dynamic> sqlMap) async {
    Database db = await createDB();
    var a = await db.insert(table, sqlMap);
    print('$a, done');
    db.close();
  }
 
  Future getData (String sqlString) async {
    Database db = await createDB();
    var b = await db.rawQuery(sqlString);
    print(b);
    db.close();
  }
//mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
  checkString () async {
    await getData('SELECT * FROM whois');
  }
 
  addString () async {
    await addData('whois', {'name':'just testing'});
  }
//mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('as'),),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: <Widget>[
          Text('ss'),
          TextField(controller: _textController,),
          RaisedButton(child: Text('add'), onPressed: addString,),
          RaisedButton(child: Text('get'), onPressed: checkString,),
        ],
      ),
    );
  }
}

flutter + bloc + sqflite demo

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import 'package:path_provider/path_provider.dart';
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path/path.dart';
import 'package:rxdart/rxdart.dart';
 
main() =>runApp(MaterialApp(home: MyApp(bloc: DataBloc(), db: DB(),),));
 
 
class MyApp extends StatelessWidget {
  MyApp({this.bloc, this.db});
  final DataBloc bloc;
  final DB db;
  TextEditingController _textController = TextEditingController();
 
  add()async{
    await db.addData('grant', {'name':'${_textController.text}'});
  }
 
  query() async{
   List result =  await db.queryData('SELECT * FROM grant');
   _textController.text = result[result.length-1]['name'];
  }
 
  delete()async{
    await db.deleteData('DELETE FROM grant WHERE id<4');
  }
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('test'),),
      body: StreamBuilder(
        stream: bloc.dataBloc.stream,
          builder: (context, snapshot){
          if (snapshot.hasData){
            return Column(
              mainAxisAlignment: MainAxisAlignment.center,
              crossAxisAlignment: CrossAxisAlignment.center,
              children: <Widget>[
                Text('head'),
                TextField(controller: _textController,),
                RaisedButton(child: Text('add'),onPressed: add,),
                RaisedButton(child: Text('query'),onPressed: query,),
                RaisedButton(child: Text('delete'),onPressed: delete,),
              ],
            );
          }else{
            return Center(child:
            RaisedButton(
                child:Text('start'),
                onPressed: (){
                  bloc.dataBloc.add('start');
                },
                ),
            );
          }
          }
      ),
    );
  }
}
 
 
class DataBloc {
  PublishSubject dataBloc = PublishSubject();
  DataBloc(){
    dataBloc.listen(onData);
  }
  void onData(value) {}
 
}
 
class DB {
 
  Future getDB() async{
    var path = (await getApplicationDocumentsDirectory()).path;
    var dbPath = join(path, 'abc', 'whois.db');
    Database _database = await openDatabase(dbPath, version: 1, onCreate: (db, ver){
      db.execute('CREATE TABLE grant (id INTEGER PRIMARY KEY, name TEXT)');
    });
    return _database;
  }
 
  Future addData (String table, Map<String, dynamic> sqlMap) async {
    Database db = await getDB();
    var ret = await db.insert(table, sqlMap);
    print('$ret done');
    db.close();
    return ret;
  }
 
  Future queryData (String sql) async{
    Database db = await getDB();
    var ret = await db.rawQuery(sql);
    db.close();
    print('$ret done');
    return ret;
  }
 
  Future deleteData (String sql) async {
    Database db = await getDB();
    var ret = await db.rawDelete(sql);
    db.close();
    print('$ret done');
    return ret;
  }
 
  Future updateData (String sql) async{
    Database db = await getDB();
    var ret = await db.rawUpdate(sql);
    db.close();
    print('$ret done');
    return ret;
  }
 
}