引入模块

dependencies:
flutter:
sdk: flutter
mysql1: ^0.20.0

mysql helper 的代码

import 'dart:async';  
import 'package:mysql1/mysql1.dart';  class MySqlHelper {  static const _host = 'localhost';  static const _port = 3333;  static const _user = 'user';  static const _db = 'table';  static const _password = 'pass';  MySqlConnection? _connection;  MySqlHelper() {  _init();  }  Future<void> _init() async {  try {  _connection = await MySqlConnection.connect(ConnectionSettings(  host: _host,  port: _port,  user: _user,  db: _db,  password: _password,  ));  } catch (e) {  // Handle the exception appropriately, e.g., log the error or rethrow.  throw Exception('Failed to connect to the database: $e');  }  }  Future<int?> create(String tableName, Map<String, dynamic> data) async {  if (_connection == null) {  throw Exception('Database connection is not initialized');  }  var columns = data.keys.join(', ');  var placeholders = List.generate(data.length, (index) => '?').join(', ');  var values = data.values.toList();  var query = 'INSERT INTO $tableName ($columns) VALUES ($placeholders)';  var result = await _connection!.query(query, values);  return result.insertId;  }  Future<List<Map<String, dynamic>>> read(String tableName) async {  if (_connection == null) {  throw Exception('Database connection is not initialized');  }  var query = 'SELECT * FROM $tableName';  var results = await _connection!.query(query);  return results.map((row) => Map.fromEntries(row.asMap().entries.map((e) => MapEntry(e.key.toString(), e.value)))).toList();  }  Future<void> update(String tableName, Map<String, dynamic> data, String whereColumn, dynamic whereValue) async {  if (_connection == null) {  throw Exception('Database connection is not initialized');  }  var sets = data.entries.map((e) => '${e.key} = ?').join(', ');  var values = data.values.toList()..add(whereValue);  var query = 'UPDATE $tableName SET $sets WHERE $whereColumn = ?';  await _connection!.query(query, values);  }  Future<void> delete(String tableName, String whereColumn, dynamic whereValue) async {  if (_connection == null) {  throw Exception('Database connection is not initialized');  }  var query = 'DELETE FROM $tableName WHERE $whereColumn = ?';  await _connection!.query(query, [whereValue]);  }  Future<void> close() async {  if (_connection != null) {  await _connection!.close();  _connection = null;  }  }  
}  // 使用示例  
void main() async {  final helper = MySqlHelper();  // 等待数据库连接初始化完成  await Future.delayed(Duration(seconds: 2)); // 仍然使用延迟作为示例，实际中应该监听连接状态  try {  // 插入数据  int? insertId = await helper.create('your_table_name', {  'column1': 'value1',  'column2': 'value2',  });  print('Inserted row with ID: $insertId');  // 读取数据  List<Map<String, dynamic>> rows = await helper.read('your_table_name');  for (var row in rows) {  print(row);  }  // 更新数据  await helper.update('your_table_name', {  'column1': 'updated_value1',  }, 'id', insertId);  // 删除数据  await helper.delete('your_table_name', 'id', insertId);  } catch (e) {  print('An error occurred: $e');  } finally {  // 关闭数据库连接  await helper.close();  }  
}

// 使用示例  
void main() async {final helper = MySqlHelper();// 等待数据库连接初始化完成  await Future.delayed(Duration(seconds: 2)); // 仍然使用延迟作为示例，实际中应该监听连接状态  try {// 插入数据  int? insertId = await helper.create('your_table_name', {'column1': 'value1','column2': 'value2',});print('Inserted row with ID: $insertId');// 读取数据  List<Map<String, dynamic>> rows = await helper.read('your_table_name');for (var row in rows) {print(row);}// 更新数据  await helper.update('your_table_name', {'column1': 'updated_value1',}, 'id', insertId);// 删除数据  await helper.delete('your_table_name', 'id', insertId);} catch (e) {print('An error occurred: $e');} finally {// 关闭数据库连接  await helper.close();}
}