Flutter使用SQLite

Flutter使用SQLite

1.添加依赖

在pubspec.yaml添加sqflite插件：

dependencies: flutter: sdk: flutter sqflite:

然后在项目根目录下执行如下命令：

$ flutter pub get

2.使用SQLite

2.1.导入

import 'package:sqflite/sqflite.dart';

2.2.打开数据库

SQLite数据库是文件系统里的一个文件，标识为一个路径。向openDatabase方法传入数据库文件的路径就可以打开数据库。

var db = await openDatabase('my_db.db');

2.3.关闭数据库

一般一个应用就用一个数据库，一般都不需要去关闭。关闭应用也就关闭了数据库。但你也可以主动关闭数据库释放资源：

await db.close();

2.4.原生SQL查询

就是没有进行过封装，直接用SQL语句查询的。

_query() async { /// 通过getDatabasesPath()方法获取数据库位置 var databasePath = await getDatabasesPath(); String path = join(databasePath, "demo.db"); /// 删除数据库 await deleteDatabase(path); /// 打开数据库 Database database = await openDatabase( path, version: 1, onCreate: (Database db, int version) async { /// 创建数据库 await db.execute( "CREATE TABLE Test(id INTEGER PRIMARY KEY,name TEXT,value INTEGER,num REAL)"); }); /// 在一个事务里插入一些数据 await database.transaction((txn) async { int id1 = await txn.rawInsert( 'INSERT INTO Test(name,value,num) VALUES("some goods",225,456.123)'); print('inserted1:$id1'); int id2 = await txn.rawInsert( 'INSERT INTO Test(name,value,num) VALUES(?,?,?)', ['another name', 45456, 3.2154]); print('inserted2:$id2'); }); /// 更新记录 int count = await database.rawUpdate( 'UPDATE Test SET name = ?,value = ? WHERE name = ?', ['updated name', '9876', 'some goods']); print('updated:$count'); /// 查询 List

2.5.SQL helpers

_querySQLHelper() async { TodoProvider todoProvider = TodoProvider(); /// 通过getDatabasesPath()方法获取数据库位置 var databasePath = await getDatabasesPath(); String path = join(databasePath, "demo.db"); /// 删除数据库 await deleteDatabase(path); /// 打开数据库，并创建todo表 await todoProvider.open(path); /// 查一条数据 Todo todo = Todo(); todo.id = 1; todo.title = "Hello"; todo.done = false; Todo td = await todoProvider.insert(todo); print('inserted:${td.toMap()}'); Todo todo2 = Todo(); todo2.id = 2; todo2.title = "Hello world"; todo2.done = false; Todo td2 = await todoProvider.insert(todo2); print('inserted:${td2.toMap()}'); /// 更新数据 todo2.title = "Big big world"; int u = await todoProvider.update(todo2); print("update:$u"); /// 删除数据 int d = await todoProvider.delete(1); print("delete:$d"); /// 查询数据 Todo dd = await todoProvider.getTodo(2); print("todo:${dd.toMap()}"); /// 关闭数据库 todoProvider.close();}/// 表名final String tableTodo = 'todo';/// _id字段final String columnId = '_id';/// title字段final String columnTitle = 'title';/// done字段final String columnDone = 'done';/// 操作todo表的工具类class TodoProvider { Database db; /// 打开数据库，并创建todo表 Future open(String path) async { db = await openDatabase(path, version: 1, onCreate: (Database db, int version) async { await db.execute('''create table $tableTodo ( $columnId integer primary key autoincrement, $columnTitle text not null, $columnDone integer not null)'''); }); } Future insert(Todo todo) async { todo.id = await db.insert(tableTodo, todo.toMap()); return todo; } Future getTodo(int id) async { List

3.完整例子

pubspec.yaml配置文件的依赖：

dependencies: flutter: sdk: flutter sqflite: ^1.3.1 collection:

collection: ^1.14.13是为了使用​​import 'package:collection/collection.dart';​​​的​​DeepCollectionEquality().equals(list, expectedList)​​。字符串的​​join​​​，要引入​​import 'package:path/path.dart';​​

import 'package:flutter/cupertino.dart';import 'package:flutter/material.dart';import 'package:fluttertoast/fluttertoast.dart';import 'package:sqflite/sqflite.dart';import 'package:collection/collection.dart';import 'package:path/path.dart';void main() => runApp(DemoApp());class DemoApp extends StatelessWidget { @override Widget build(BuildContext context) { return new MaterialApp( title: 'Image Picker Demo', home: new MyHomePage(), ); }}class MyHomePage extends StatefulWidget { @override _MyHomePageState createState() => _MyHomePageState();}class _MyHomePageState extends State { @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text("Hello World"), ), body: Center( child: RaisedButton( child: Text("Click"), onPressed: () { Fluttertoast.showToast(msg: "Hello world", textColor: Colors.black); _querySQLHelper(); }, ), ), ); }}_query() async { /// 通过getDatabasesPath()方法获取数据库位置 var databasePath = await getDatabasesPath(); String path = join(databasePath, "demo.db"); /// 删除数据库 await deleteDatabase(path); /// 打开数据库 Database database = await openDatabase(path, version: 1, onCreate: (Database db, int version) async { /// 创建数据库 await db.execute( "CREATE TABLE Test(id INTEGER PRIMARY KEY,name TEXT,value INTEGER,num REAL)"); }); /// 在一个事务里插入一些数据 await database.transaction((txn) async { int id1 = await txn.rawInsert( 'INSERT INTO Test(name,value,num) VALUES("some goods",225,456.123)'); print('inserted1:$id1'); int id2 = await txn.rawInsert( 'INSERT INTO Test(name,value,num) VALUES(?,?,?)', ['another name', 45456, 3.2154]); print('inserted2:$id2'); }); /// 更新记录 int count = await database.rawUpdate( 'UPDATE Test SET name = ?,value = ? WHERE name = ?', ['updated name', '9876', 'some goods']); print('updated:$count'); /// 查询 List

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