iv_and/db_helper.dart

import 'package:sqflite/sqflite.dart';
import 'package:path_provider/path_provider.dart';
import 'dart:io' as io;

class DbHelper {
  static Database? _database;

  Future<Database> get database async {
    if (_database != null) return _database!;
    _database = await initDb();
    return _database!;
  }

  initDb() async {
    io.Directory documentsDirectory = await getApplicationDocumentsDirectory();
    String path = '${documentsDirectory.path}/invoice.db';
    var db = await openDatabase(path, version: 1, onCreate: _onCreate);
    return db;
  }

  void _onCreate(Database db, int version) async {
    await db.execute('''
      CREATE TABLE customers (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        name TEXT,
        phone TEXT,
        address TEXT,
        email TEXT
      )
    ''');

    await db.execute('''
      CREATE TABLE products (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        name TEXT,
        unit_price REAL,
        discount REAL
      )
    ''');

    await db.execute('''
      CREATE TABLE invoices (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        customer_id INTEGER,
        date TEXT,
        total REAL,
        tax REAL,
        discount_total REAL
      )
    ''');

    await db.execute('''
      CREATE TABLE invoice_items (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        invoice_id INTEGER,
        product_id INTEGER,
        quantity INTEGER,
        unit_price REAL,
        discount REAL
      )
    ''');
  }
}