flutter 开发中常用的数库插件sqflite
插件地址：sqflite | Flutter Package (pub.dev)
官方给出的例子
// 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();
使用方法
- 创建数据库
String databasesPath = await getDatabasesPath();
String path = join(databasesPath, '数据库名字.db');
- 打开数据库
Database database = await openDatabase(
path,
version: VERSION,
onCreate: (Database db, int version) async {
//路径下没有数据库文件时创建数据库的回调
},
onUpgrade: (Database db, int oldVersion, int newVersion) async {
// 数据库升级回调
},
onOpen: (Database db) async {
// 打开数据库的回调
},
);
- 数据操作
- 创建表
// 创建表person
database.execute('CREATE TABLE person (id INTEGER PRIMARY KEY, name TEXT, age INTEGER)');
- 增
await database.insert(
'person',
{'name': 'Civet', 'age': '18'},
conflictAlgorithm: ConflictAlgorithm.replace,
);
- 删
await database.delete(
'person',
where: 'name = ?',
whereArgs: ['Civet'],
);
- 改
await database.update(
'person',
{'name': 'Civet', 'age': '19'},
where: 'name = ?',
whereArgs: ['Civet'],
);
- 查
final List<Map<String, dynamic>> maps = await database.query('person');
- 关闭数据库
await database.close();
- 删除数据库
await deleteDatabase(path);
