title: the method join isn't defined flutter sqflite
body: <p>Android studio is giving me 2 problems according to the following example: <a href="https://pub.dartlang.org/packages/sqflite" rel="noreferrer">https://pub.dartlang.org/packages/sqflite</a></p>
  
  <p>1) The method <code>join</code> isn't defined for the class <code>uploadIntoDb</code></p>
  
  <p>2) Undefined class <code>DeepCollectionEquality</code></p>
  
  <p>There is my so simple code :</p>
  
  <pre><code>import 'package:flutter/material.dart';
  import 'dart:async';
  import 'package:sqflite/sqflite.dart';
  
  class UploadPage extends StatefulWidget {
    @override
    State&lt;StatefulWidget&gt; createState(){
      return new UploadPageState();
    }
  }
  
  class UploadPageState extends State&lt;UploadPage&gt;
      with SingleTickerProviderStateMixin {
    @override
    void initState(){
      super.initState();
    }
  
    @override
    Widget build(BuildContext context) {
  
  
      return null;
    }
  
    Future&lt;void&gt; uploadIntoDb(String valueToUpload) async{
      // Get a location using getDatabasesPath
      var databasesPath = await getDatabasesPath();
      String path = join(databasesPath, 'poa.db');//FIRST PROBLEM
  
  
  // open the database
      Database database = await openDatabase(path, version: 1,
          onCreate: (Database db, int version) async {
            // When creating the db, create the table
            await db.execute(
                'CREATE TABLE Test (id INTEGER PRIMARY KEY, name TEXT, value INTEGER, num REAL)');
          });
  
  // Insert some records in a transaction
      await database.transaction((txn) async {
        int id1 = await txn.rawInsert(
            'INSERT INTO Test(name, value, num) VALUES("some name", 1234, 456.789)');
        print('inserted1: $id1');
        int id2 = await txn.rawInsert(
            'INSERT INTO Test(name, value, num) VALUES(?, ?, ?)',
            ['another name', 12345678, 3.1416]);
        print('inserted2: $id2');
      });
  
  // Update some record
      int count = await database.rawUpdate(
          'UPDATE Test SET name = ?, VALUE = ? WHERE name = ?',
          ['updated name', '9876', 'some name']);
      print('updated: $count');
  
  // Get the records
      List&lt;Map&gt; list = await database.rawQuery('SELECT * FROM Test');
      List&lt;Map&gt; expectedList = [
        {'name': 'updated name', 'id': 1, 'value': 9876, 'num': 456.789},
        {'name': 'another name', 'id': 2, 'value': 12345678, 'num': 3.1416}
      ];
      print(list);
      print(expectedList);
      assert(const DeepCollectionEquality().equals(list, expectedList));//SECOND PROBLEM
  
  // Count the records
      count = Sqflite
          .firstIntValue(await database.rawQuery('SELECT COUNT(*) FROM Test'));
      assert(count == 2);
  
  // Delete a record
      count = await database
          .rawDelete('DELETE FROM Test WHERE name = ?', ['another name']);
      assert(count == 1);
  
  // Close the database
      await database.close();
    }
  }
  </code></pre>
  
  <p>PS: Yes I included the dependency: <code>sqflite: ^1.1.0</code></p>