Question

我正在尝试创建一个可以访问数据库，加载数据以及用户是否添加任何新字段的应用程序，以将数据保存回数据库。目前，我可以将数据加载到应用程序中，但由于上面给出的错误，我仍然无法保存任何更改。

这是保存方法

    private void Save_Click(object sender, RoutedEventArgs e)
    {
        dataSource.updateDataSet(dataSet);
    }

这是SimeDataSource文件

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using MySql.Data.MySqlClient;
using System.Data;

class SimpleDataSource : IDisposable
{
    MySqlConnection conn;
    MySqlDataAdapter adapter = new MySqlDataAdapter();

public SimpleDataSource(string server, string database, int port,
    string user, string password)
{
    Connect(server, database, port, user, password); 
}

public void Connect(string server, string database, int port,
    string user, string password)
{

    string connectionString = "server=" + server + ";database=" + database + ";port=" + port + ";user=" + user + ";password=" + password;
    try
    {
        conn = new MySqlConnection(connectionString);
        conn.Open();
    }
    catch (MySqlException e)
    {
        Console.WriteLine("Error: {0}", e.ToString());
    }
    finally
    {
        if (conn == null)
        {
            conn.Close();
        }
    }
}

public MySqlDataReader Query(string queryString)
{
    // TODO: Declares MySqlDataReader and MySqlCommand objects.
    // When the MySqlCommand object is executed with the query
    // string, the return value will be assigned to the MySqlDataReader
    // object. This object is then returned with the "return" keyword.
    try
    {
        MySqlCommand cmd = new MySqlCommand(queryString, conn);
        cmd.ExecuteNonQuery();
    }
    catch (MySqlException e)
    {
        Console.WriteLine("Error: {0}", e.ToString());
    }
    return null;
}

public void Update(string updateString)
{
    try
    {
        MySqlCommand cmd = new MySqlCommand(updateString, conn);
        cmd.ExecuteNonQuery();
    }
    catch (MySqlException e)
    {
        Console.WriteLine("Error: {0}", e.ToString());
    }
}

public void Dispose()
{
    if (conn != null)
        conn.Dispose();
}

public void QueryPreparedStatement(string queryString, Dictionary<string, string> values)
{
    try
    {
        MySqlCommand cmd = new MySqlCommand(queryString, conn);
        foreach (string key in values.Keys)
        {
            cmd.Parameters.AddWithValue("@" + key, values[key]);
        }
        cmd.ExecuteNonQuery();
    }
    catch (MySqlException ex)
    {
        Console.WriteLine("Error: {0}", ex.ToString());
    }

}

public DataTable DataTableQuery(string sqlQuery)
{
    DataTable dt = new DataTable();
    MySqlCommand cmd = new MySqlCommand(sqlQuery, conn);
    MySqlDataAdapter adapter = new MySqlDataAdapter(cmd);
    adapter.SelectCommand = cmd;
    try
    {
        adapter.Fill(dt);
        return dt;
    }
    catch (MySqlException ex)
    {
        Console.WriteLine("Error: {0}", ex.ToString());
        return null;
    }

}

public static void updateDataSet(DataSet dataSet)
{
    try
    {
        MySqlDataAdapter adapter = new MySqlDataAdapter();
        adapter.Update(dataSet);
    }
    catch (MySqlException ex)
    {
        Console.WriteLine("Error: {0}", ex.ToString());
    }
}

}

编辑：

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace Application_Development_Project
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private SimpleDataSource dataSource;
        private DataSet dataSet;

        public MainWindow()
        {
            InitializeComponent();
            dataSource = new SimpleDataSource
            ("*****","*****",*****,"*****","*****");
        }

        public void SimpleDataSource(string server, string database, int port, string user, string password)
        {
            string connectionString = "server=" + server + ";database=" + database + ";port=" + port + ";user=" + user + ";password=" + password;

        }

        private void Load_Click(object sender, RoutedEventArgs e)
        {
            DataTable dt = dataSource.DataTableQuery("SELECT * FROM Company");
            dataGrid.ItemsSource = dt.DefaultView;
        }

        private void Save_Click(object sender, RoutedEventArgs e)
        {
            SimpleDataSource.updateDataSet(dataSet);
        }

    }
}

Answer 1

您已将//Checking user's city __block NSString *userCity; [[GMSGeocoder geocoder]reverseGeocodeCoordinate:self.locationManager.location.coordinate completionHandler:^(GMSReverseGeocodeResponse *response, NSError *error) { if (error) { NSLog(@"%@",[error description]); } userCity=[[[response results] firstObject] locality]; }]; //Checking store's city __block NSString *storeCity; [[GMSGeocoder geocoder]reverseGeocodeCoordinate:arounder.radiusCircularRegion.center completionHandler:^(GMSReverseGeocodeResponse *response, NSError *error) { if (error) { NSLog(@"%@",[error description]); } arounderCity=[[[response results] firstObject] locality]; }]; if ([userCity isEqualToString:arounderCity]) { return YES; }声明为updateDataSet。

静态意味着您在Type上调用它，而不是该类型的实例（如错误所示）。

不是这样：public static void updateDataSet(DataSet dataSet)

但是：dataSource.updateDataSet(dataSet);

编辑：你还应该将SimpleDataSource.updateDataSet(dataSet);中的SimpleDataSource方法重命名为其他方法，否则编译器会认为你的意思是指方法而不是类。

“无法使用实例引用访问;请使用类型名称对其进行限定”

1 个答案: