Question

首先，我是C＃和Visual Studio的新手。我按照教程如何从MySql表填充DataGridView。我多次检查复制错误，但我没有找到任何错误。代码是这样的：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace DataGridMain
{
    public partial class Form1 : Form
    {
        private string server;
        private string database;
        private string uid;
        private string password;
        private MySqlConnection connection;
        private MySqlDataAdapter mySqlDataAdapter;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {  
         server = "localhost";
         database = "elphoapp";
         uid = "username";
         password = "password";
         string connectionString;
         connectionString = "SERVER=" + server + ";" + "DATABASE=" + database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";";

    connection = new MySqlConnection(connectionString);

    if (this.OpenConnection() == true)
    {
        mySqlDataAdapter = new MySqlDataAdapter("select * from users", connection);
        DataSet DS = new DataSet();
        mySqlDataAdapter.Fill(DS);
        dataGridView1.DataSource = DS.Tables[0];
        this.CloseConnection();
    }


        }

private bool OpenConnection()
{
    try
    {
        connection.Open();
        return true;
    }
    catch (MySqlException ex)
    {
        switch (ex.Number)
        {
            case 0:
                MessageBox.Show("Cannot connect to server. Contact administrator");
                break;
            case 1045:
                MessageBox.Show("Invalid username/password, please try again");
                break;
            default:
                MessageBox.Show(ex.Message);
                break;
        }
        return false;
    }
}
        private bool CloseConnection()
{
    try
    {
        connection.Close();
        return true;
    }
    catch (MySqlException ex)
    {
        MessageBox.Show(ex.Message);
        return false;
    }
}
    }
    }

我似乎无法找到问题，也没有显示错误。

Answer 1

由于您是Visual Studio的新手，我的建议是您必须学习的第一件事就是调试。它会为你节省很多时间。在这种情况下，在form_load中放置一个断点并逐步运行代码。您可以通过这种方式查看正在发生的事情，并检查所有变量。我之所以这样说是因为我无法在代码中看到任何错误，所以可能您甚至没有连接到数据库。调试代码可能会看到原因

Answer 2

好的，我想通了！我所要做的就是从Form1（）函数中调用Form1_Load。目前一切似乎都运转良好。谢谢，C＃充满了该死的惊喜......

从Mysql数据库填充DataGrid

2 个答案: