Flutter的SQLite插件。支持iOS和Android。
- 支持交易和批次打开期间
- 自动版本管理
- 插入/查询/更新/删除查询的助手
- 在iOS和Android上的后台线程中执行数据库操作
添加依赖
dependencies:
sqflite: ^1.1.1安装
flutter packages get导入
import 'package:sqflite/sqflite.dart';原生SQL查询
// Get a location using getDatabasesPath
var databasesPath = await getDatabasesPath();
String path = join(databasesPath, 'demo.db');
// Delete the database
await deleteDatabase(path);
// 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<Map> list = await database.rawQuery('SELECT * FROM Test');
List<Map> 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));
// 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();SQL helpers
final String tableTodo = 'todo';
final String columnId = '_id';
final String columnTitle = 'title';
final String columnDone = 'done';
class Todo {
int id;
String title;
bool done;
Map<String, dynamic> toMap() {
var map = <String, dynamic>{
columnTitle: title,
columnDone: done == true ? 1 : 0
};
if (id != null) {
map[columnId] = id;
}
return map;
}
Todo();
Todo.fromMap(Map<String, dynamic> map) {
id = map[columnId];
title = map[columnTitle];
done = map[columnDone] == 1;
}
}
class TodoProvider {
Database db;
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,
$columnDone integer not null)
''');
});
}
Future<Todo> insert(Todo todo) async {
todo.id = await db.insert(tableTodo, todo.toMap());
return todo;
}
Future<Todo> getTodo(int id) async {
List<Map> maps = await db.query(tableTodo,
columns: [columnId, columnDone, columnTitle],
where: '$columnId = ?',
whereArgs: [id]);
if (maps.length > 0) {
return Todo.fromMap(maps.first);
}
return null;
}
Future<int> delete(int id) async {
return await db.delete(tableTodo, where: '$columnId = ?', whereArgs: [id]);
}
Future<int> update(Todo todo) async {
return await db.update(tableTodo, todo.toMap(),
where: '$columnId = ?', whereArgs: [todo.id]);
}
Future close() async => db.close();
}
读结果
假设以下读取结果：
List<Map<String, dynamic>> records = await db.query('my_table');
结果映射项是只读
// get the first record
Map<String, dynamic> mapRead = records.first;
// Update it in memory...this will throw an exception
mapRead['my_column'] = 1;
// Crash... `mapRead` is read-only
如果想在内存中修改，需要创建一个新的映射
// get the first record
Map<String, dynamic> map = Map<String, dynamic>.from(mapRead);
// Update it in memory now
map['my_column'] = 1;
事务
不要使用数据库，而只使用事务中的Transaction对象来访问数据库
await database.transaction((txn) async {
// Ok
await txn.execute('CREATE TABLE Test1 (id INTEGER PRIMARY KEY)');
// DON'T use the database object in a transaction
// this will deadlock!
await database.execute('CREATE TABLE Test2 (id INTEGER PRIMARY KEY)');
});
如果回调没有引发错误，则提交事务。如果抛出错误，则取消该事务。因此，以一种方式回滚事务就是抛出异常。
批量支持
要避免使用dart和本机代码之间的乒乓，可以使用Batch：
batch = db.batch();
batch.insert('Test', {'name': 'item'});
batch.update('Test', {'name': 'new_item'}, where: 'name = ?', whereArgs: ['item']);
batch.delete('Test', where: 'name = ?', whereArgs: ['item']);
results = await batch.commit();
获取每个操作的结果都有成本（插入ID和更新和删除的更改次数），尤其是在执行额外SQL请求的Android上。如果您不关心结果并担心大批量的性能，您可以使用
await batch.commit(noResult: true);
警告，在事务期间，在提交事务之前不会提交批处理
await database.transaction((txn) async {
var batch = txn.batch();
// ...
// commit but the actual commit will happen when the transaction is committed
// however the data is available in this transaction
await batch.commit();
// ...
});
默认情况下，批处理在遇到错误时会立即停止（通常会还原未提交的更改）。您可以忽略错误，以便即使一个操作失败也会运行并提交每个成功的操作：
await batch.commit(continueOnError: true);
表和列名称
通常，最好避免将SQLite关键字用于实体名称。如果使用以下任何名称：
"add","all","alter","and","as","autoincrement","between","case","check","collate","commit","constraint","create","default","deferrable","delete","distinct","drop","else","escape","except","exists","foreign","from","group","having","if","in","index","insert","intersect","into","is","isnull","join","limit","not","notnull","null","on","or","order","primary","references","select","set","table","then","to","transaction","union","unique","update","using","values","when","where"
助手将逃脱名称，即
db.query('table')
将等同于在表名周围手动添加双引号（这里容易引起混淆的表）
db.rawQuery('SELECT * FROM "table"');
但是在任何其他原始语句（包括orderBy，where，groupBy）中，请确保使用双引号正确地转义名称。例如，请参阅下面的列名称组未在columns参数中进行转义，但在where参数中进行转义。
db.query('table', columns: ['group'], where: '"group" = ?', whereArgs: ['my_group']);
支持的SQLite类型
DateTime不是受支持的SQLite类型。我个人将它们存储为int（millisSinceEpoch）或字符串（iso8601）
bool不是受支持的SQLite类型。使用INTEGER和0和1值。
- INTEGER
Dart type: int
Supported values: from -2^63 to 2^63 - 1
- REAL
Dart type: num
- TEXT
Dart type: String
- BLOB
Dart type: Uint8List
Dart type List