Flutter数据库Sqflite之增删改查
简介
- sqflite是Flutter的SQLite插件，支持iOS和Android，目前官方版本是sqflite1.1.3
- sqflite插件地址：https://pub.dartlang.org/packages/sqflite#-readme-tab-
- sqflite支持事务和批处理
- sqflite支持打开期间自动版本管理
- sqflite支持插入/查询/更新/删除查询的助手
- sqflite支持在iOS和Android上的后台线程中执行数据库操作
更多Flutter相关内容可以访问我的Github
关键API
- 获取数据库的路径
var databasesPath = await getDatabasesPath(); String path = join(databasesPath, 'demo.db');- 打开数据库
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)'); });- 使用事务插入一条记录
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'); });- 更新一条记录
int count = await database.rawUpdate(
'UPDATE Test SET name = ?, VALUE = ? WHERE name = ?', ['updated name', '9876', 'some name']); print('updated: $count');- 查询记录
List<Map> list = await database.rawQuery('SELECT * FROM Test');- 查询总记录数
count = Sqflite.firstIntValue(await database.rawQuery('SELECT COUNT(*) FROM Test'));- 删除一条记录
count = await database.rawDelete('DELETE FROM Test WHERE name = ?', ['another name']);- 关闭数据库
await database.close();使用
- 首先创建model
class User { String name; int age; int id; Map<String, dynamic> toMap() { var map = new Map<String, dynamic>(); map['name'] = name; map['age'] = age; map['id'] = id; return map; } static User fromMap(Map<String, dynamic> map) { User user = new User(); user.name = map['name']; user.age = map['age']; user.id = map['id']; return user; } static List<User> fromMapList(dynamic mapList) { List<User> list = new List(mapList.length); for (int i = 0; i < mapList.length; i++) { list[i] = fromMap(mapList[i]); } return list; } }- 创建db_helper，数据库帮助类
class DatabaseHelper { static final DatabaseHelper _instance = DatabaseHelper.internal(); factory DatabaseHelper() => _instance; final String tableName = "table_user"; final String columnId = "id"; final String columnName = "name"; final String columnAge = "age"; static Database _db; Future<Database> get db async { if (_db != null) { return _db; } _db = await initDb(); return _db; } DatabaseHelper.internal(); initDb() async { var databasesPath = await getDatabasesPath(); String path = join(databasesPath, 'sqflite.db'); var ourDb = await openDatabase(path, version: 1, onCreate: _onCreate); return ourDb; } //创建数据库表 void _onCreate(Database db, int version) async { await db.execute( "create table $tableName($columnId integer primary key,$columnName text not null ,$columnAge integer not null )"); print("Table is created"); } //插入 Future<int> saveItem(User user) async { var dbClient = await db; int res = await dbClient.insert("$tableName", user.toMap()); print(res.toString()); return res; } //查询 Future<List> getTotalList() async { var dbClient = await db; var result = await dbClient.rawQuery("SELECT * FROM $tableName "); return result.toList(); } //查询总数 Future<int> getCount() async { var dbClient = await db; return Sqflite.firstIntValue(await dbClient.rawQuery( "SELECT COUNT(*) FROM $tableName" )); } //按照id查询 Future<User> getItem(int id) async { var dbClient = await db; var result = await dbClient.rawQuery("SELECT * FROM $tableName WHERE id = $id"); if (result.length == 0) return null; return User.fromMap(result.first); } //清空数据 Future<int> clear() async { var dbClient = await db; return await dbClient.delete(tableName); } //根据id删除 Future<int> deleteItem(int id) async { var dbClient = await db; return await dbClient.delete(tableName, where: "$columnId = ?", whereArgs: [id]); } //修改 Future<int> updateItem(User user) async { var dbClient = await db; return await dbClient.update("$tableName", user.toMap(), where: "$columnId = ?", whereArgs: [user.id]); } //关闭 Future close() async { var dbClient = await db; return dbClient.close(); } }- 在进行页面增删该查操作
class DataAppPage extends StatefulWidget { @override State<StatefulWidget> createState() { return new _DataAppPageState(); } } class _DataAppPageState extends State<DataAppPage> { List<User> _datas = new List(); var db = DatabaseHelper(); Future<Null> _refresh() async { _query(); } @override void initState() { super.initState(); _getDataFromDb(); } _getDataFromDb() async { List datas = await db.getTotalList(); if (datas.length > 0) { //数据库有数据 datas.forEach((user) { User item = User.fromMap(user); _datas.add(item); }); } else { //数据库没有数据 User user = new User(); user.name = "张三"; user.age = 10; user.id = 1; User user2 = new User(); user2.name = "李四"; user2.age = 12; user2.id = 2; await db.saveItem(user); await db.saveItem(user2); _datas.add(user); _datas.add(user2); } setState(() {}); } //添加 Future<Null> _add() async { User user = new User(); user.name = "我是增加的"; user.age = 33; await db.saveItem(user); _query(); } //删除,默认删除第一条数据 Future<Null> _delete() async { List datas = await db.getTotalList(); if (datas.length > 0) { //修改第一条数据 User user = User.fromMap(datas[0]); db.deleteItem(user.id); _query(); } } //修改，默认修改第一条数据 Future<Null> _update() async { List datas = await db.getTotalList(); if (datas.length > 0) { //修改第一条数据 User u = User.fromMap(datas[0]); u.name = "我被修改了"; db.updateItem(u); _query(); } } //查询 Future<Null> _query() async { _datas.clear(); List datas = await db.getTotalList(); if (datas.length > 0) { //数据库有数据 datas.forEach((user) { User dataListBean = User.fromMap(user); _datas.add(dataListBean); }); } setState(() {}); } @override Widget build(BuildContext context) { return new Scaffold( appBar: AppBar( title: Text("sqflite学习"), centerTitle: true, actions: <Widget>[ new PopupMenuButton( onSelected: (String value) { switch (value) { case "增加": _add(); break; case "删除": _delete(); break; case "修改": _update(); break; case "查询": _query(); break; } }, itemBuilder: (BuildContext context) => <PopupMenuItem<String>>[ new PopupMenuItem(value: "增加", child: new Text("增加")), new PopupMenuItem(value: "删除", child: new Text("删除")), new PopupMenuItem(value: "修改", child: new Text("修改")), new PopupMenuItem(value: "查询", child: new Text("查询")), ]) ], ), body: RefreshIndicator( displacement: 15, onRefresh: _refresh, child: ListView.separated( itemBuilder: _renderRow, physics: new AlwaysScrollableScrollPhysics(), separatorBuilder: (BuildContext context, int index) { return Container( height: 0.5, color: Colors.black38, ); }, itemCount: _datas.length), ), ); } Widget _renderRow(BuildContext context, int index) { return Column( crossAxisAlignment: CrossAxisAlignment.start, children: <Widget>[ Padding( padding: EdgeInsets.all(5), child: Text("姓名：" + _datas[index].name)), Padding( padding: EdgeInsets.all(5), child: Text("年龄：" + _datas[index].age.toString())), ], ); } }
,
简介
- sqflite是Flutter的SQLite插件，支持iOS和Android，目前官方版本是sqflite1.1.3
- sqflite插件地址：https://pub.dartlang.org/packages/sqflite#-readme-tab-
- sqflite支持事务和批处理
- sqflite支持打开期间自动版本管理
- sqflite支持插入/查询/更新/删除查询的助手
- sqflite支持在iOS和Android上的后台线程中执行数据库操作
更多Flutter相关内容可以访问我的Github
关键API
- 获取数据库的路径
var databasesPath = await getDatabasesPath(); String path = join(databasesPath, 'demo.db');- 打开数据库
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)'); });- 使用事务插入一条记录
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'); });- 更新一条记录
int count = await database.rawUpdate(
'UPDATE Test SET name = ?, VALUE = ? WHERE name = ?', ['updated name', '9876', 'some name']); print('updated: $count');- 查询记录
List<Map> list = await database.rawQuery('SELECT * FROM Test');- 查询总记录数
count = Sqflite.firstIntValue(await database.rawQuery('SELECT COUNT(*) FROM Test'));- 删除一条记录
count = await database.rawDelete('DELETE FROM Test WHERE name = ?', ['another name']);- 关闭数据库
await database.close();使用
- 首先创建model
class User { String name; int age; int id; Map<String, dynamic> toMap() { var map = new Map<String, dynamic>(); map['name'] = name; map['age'] = age; map['id'] = id; return map; } static User fromMap(Map<String, dynamic> map) { User user = new User(); user.name = map['name']; user.age = map['age']; user.id = map['id']; return user; } static List<User> fromMapList(dynamic mapList) { List<User> list = new List(mapList.length); for (int i = 0; i < mapList.length; i++) { list[i] = fromMap(mapList[i]); } return list; } }- 创建db_helper，数据库帮助类
class DatabaseHelper { static final DatabaseHelper _instance = DatabaseHelper.internal(); factory DatabaseHelper() => _instance; final String tableName = "table_user"; final String columnId = "id"; final String columnName = "name"; final String columnAge = "age"; static Database _db; Future<Database> get db async { if (_db != null) { return _db; } _db = await initDb(); return _db; } DatabaseHelper.internal(); initDb() async { var databasesPath = await getDatabasesPath(); String path = join(databasesPath, 'sqflite.db'); var ourDb = await openDatabase(path, version: 1, onCreate: _onCreate); return ourDb; } //创建数据库表 void _onCreate(Database db, int version) async { await db.execute( "create table $tableName($columnId integer primary key,$columnName text not null ,$columnAge integer not null )"); print("Table is created"); } //插入 Future<int> saveItem(User user) async { var dbClient = await db; int res = await dbClient.insert("$tableName", user.toMap()); print(res.toString()); return res; } //查询 Future<List> getTotalList() async { var dbClient = await db; var result = await dbClient.rawQuery("SELECT * FROM $tableName "); return result.toList(); } //查询总数 Future<int> getCount() async { var dbClient = await db; return Sqflite.firstIntValue(await dbClient.rawQuery( "SELECT COUNT(*) FROM $tableName" )); } //按照id查询 Future<User> getItem(int id) async { var dbClient = await db; var result = await dbClient.rawQuery("SELECT * FROM $tableName WHERE id = $id"); if (result.length == 0) return null; return User.fromMap(result.first); } //清空数据 Future<int> clear() async { var dbClient = await db; return await dbClient.delete(tableName); } //根据id删除 Future<int> deleteItem(int id) async { var dbClient = await db; return await dbClient.delete(tableName, where: "$columnId = ?", whereArgs: [id]); } //修改 Future<int> updateItem(User user) async { var dbClient = await db; return await dbClient.update("$tableName", user.toMap(), where: "$columnId = ?", whereArgs: [user.id]); } //关闭 Future close() async { var dbClient = await db; return dbClient.close(); } }- 在进行页面增删该查操作
class DataAppPage extends StatefulWidget { @override State<StatefulWidget> createState() { return new _DataAppPageState(); } } class _DataAppPageState extends State<DataAppPage> { List<User> _datas = new List(); var db = DatabaseHelper(); Future<Null> _refresh() async { _query(); } @override void initState() { super.initState(); _getDataFromDb(); } _getDataFromDb() async { List datas = await db.getTotalList(); if (datas.length > 0) { //数据库有数据 datas.forEach((user) { User item = User.fromMap(user); _datas.add(item); }); } else { //数据库没有数据 User user = new User(); user.name = "张三"; user.age = 10; user.id = 1; User user2 = new User(); user2.name = "李四"; user2.age = 12; user2.id = 2; await db.saveItem(user); await db.saveItem(user2); _datas.add(user); _datas.add(user2); } setState(() {}); } //添加 Future<Null> _add() async { User user = new User(); user.name = "我是增加的"; user.age = 33; await db.saveItem(user); _query(); } //删除,默认删除第一条数据 Future<Null> _delete() async { List datas = await db.getTotalList(); if (datas.length > 0) { //修改第一条数据 User user = User.fromMap(datas[0]); db.deleteItem(user.id); _query(); } } //修改，默认修改第一条数据 Future<Null> _update() async { List datas = await db.getTotalList(); if (datas.length > 0) { //修改第一条数据 User u = User.fromMap(datas[0]); u.name = "我被修改了"; db.updateItem(u); _query(); } } //查询 Future<Null> _query() async { _datas.clear(); List datas = await db.getTotalList(); if (datas.length > 0) { //数据库有数据 datas.forEach((user) { User dataListBean = User.fromMap(user); _datas.add(dataListBean); }); } setState(() {}); } @override Widget build(BuildContext context) { return new Scaffold( appBar: AppBar( title: Text("sqflite学习"), centerTitle: true, actions: <Widget>[ new PopupMenuButton( onSelected: (String value) { switch (value) { case "增加": _add(); break; case "删除": _delete(); break; case "修改": _update(); break; case "查询": _query(); break; } }, itemBuilder: (BuildContext context) => <PopupMenuItem<String>>[ new PopupMenuItem(value: "增加", child: new Text("增加")), new PopupMenuItem(value: "删除", child: new Text("删除")), new PopupMenuItem(value: "修改", child: new Text("修改")), new PopupMenuItem(value: "查询", child: new Text("查询")), ]) ], ), body: RefreshIndicator( displacement: 15, onRefresh: _refresh, child: ListView.separated( itemBuilder: _renderRow, physics: new AlwaysScrollableScrollPhysics(), separatorBuilder: (BuildContext context, int index) { return Container( height: 0.5, color: Colors.black38, ); }, itemCount: _datas.length), ), ); } Widget _renderRow(BuildContext context, int index) { return Column( crossAxisAlignment: CrossAxisAlignment.start, children: <Widget>[ Padding( padding: EdgeInsets.all(5), child: Text("姓名：" + _datas[index].name)), Padding( padding: EdgeInsets.all(5), child: Text("年龄：" + _datas[index].age.toString())), ], ); } }