如何使用datagridview显示数据库中的值 [英] How to use datagridview to display values from a database

问题描述

我正在通过如何使用C＃连接到MySQL来学习本教程 [ ^ ]





出于某种原因，我得到名称

I am following the tutorial by How to Connect to MySQL Using C#[^]


For some reason I am getting the name

dataGridView1 does not exists in the current context at the line 


dataGridView1.DataSource = ds.Tables[0].DefaultView;


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 connect4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            //string MyConnectionString = "server=localhost;database=testdb;uid=root;pwd=;" ; 
        }

        private void button1_Click(object sender, EventArgs e)

        {

            string MyConnectionString = "server=localhost;database=testdb;uid=root;pwd=;" ; 

            //int MobileNo;
            //string Mobile = Mobile.Text;

            //int.TryParse(Mobile, out MobileNo);

            MySqlConnection con = new MySqlConnection(MyConnectionString);

            MySqlCommand cmd;

            con.Open();

            MessageBox.Show("connection open"); 


            try {

                cmd = con.CreateCommand();
                cmd.CommandText = "INSERT INTO  phonebook(Id, Name, MobileNo) VALUES (@ID, @Name,@MobileNo)";

                cmd.Parameters.AddWithValue("@Id", int.Parse(Id.Text));

                cmd.Parameters.AddWithValue("@Name", txtName.Text);

                cmd.Parameters.AddWithValue("@MobileNo", int.Parse(Mobile.Text));

                cmd.ExecuteNonQuery();

                MessageBox.Show("Values inserted"); 

            }

            catch (Exception)
            {

                throw;
                //MessageBox.Show("query failed"); 

            }


            finally
            {

                if (con.State == ConnectionState.Open)

                {
                    con.Close();

                    MessageBox.Show("connection closed");
                    LoadData();
                }
            }

        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {

        }

        
        private void LoadData()
        {

            string MyConnectionString = "server=localhost;database=testdb;uid=root;pwd=;"; 

            MySqlConnection con = new MySqlConnection(MyConnectionString);


            con.Open();

            MessageBox.Show("connection open");

            try
            {
                MySqlCommand cmd = con.CreateCommand();

                cmd.CommandText = "SELECT * FROM  phonebook";

                MySqlDataAdapter adap = new MySqlDataAdapter(cmd);

                DataSet ds = new DataSet();

                adap.Fill(ds);

                //bindingSource1.DataSource = ds;

                dataGridView1.DataSource = ds.Tables[0].DefaultView;


            }

            catch (Exception)
            {
                throw;
            }


            finally {


                if (con.State == ConnectionState.Open)
                {

                    con.Close();
                }
            
            
            
            }
            
        
        
        }


    }
}

我尝试过：



* ----------------------------------------- ------------------------------------------------- * -------------------------------------------------- -------------------------------------------------- -------------------------------------------------- -------------------------

What I have tried:

*------------------------------------------------------------------------------------------*-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

推荐答案

ID和Mobile不以txt为前缀（大概是表格上控件的名称。



你应该做的是：

在管理工具中打开你的数据库（ SSMS用于sql server，不知道是什么用于MySql）

检查记录是否已正确保存



在Button_Click中放置一个断点事件并逐步完成方法，检查val输入的用户。

ID and Mobile are not prefixed with txt (presumably the name of the control on the form.

What you should have done is:
open your database in the management tool (SSMS for sql server, not sure what for MySql)
Check that the record has been save correctly

Put a break point in the Button_Click event and stepped through the method, checking the values of the input.

这篇关于如何使用datagridview显示数据库中的值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！