當數據庫中的數據發生變化時更新變量

Question

這裏我有三個變量，變量由數據庫中的數據填充，並使用標籤將其顯示在屏幕上。 但是，當我更改數據庫中的數據時，變量不會自動更改。 我會嘗試做什麼是創建一個變量，以便在數據庫中的數據更改時自動更改。 但我不知道該怎麼做，因爲我是新手。

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; 
using MySql.Data.MySqlClient; 
using System.Data.SqlClient; 

namespace vendingInterface 
{ 
    public partial class Form1 : Form 
    { 

     public MySqlConnection conn; 
     private string server; 
     private string database; 
     private string uid; 
     private string password; 
     private string produk11; 
     private string produk22; 
     private string produk33; 


     public Form1() 
     { 
      bacadatabase(); 
      InitializeComponent(); 
      info(); 

     } 

我顯示使用標籤

 private void info() 
     { 
      lbl_produk1.Text = "Jumlah Produk 1 = " + produk11 + " Buah"; 
      lbl_produk2.Text = "Jumlah Produk 2 = " + produk22 + " Buah"; 
      lbl_produk3.Text = "Jumlah Produk 3 = " + produk33 + " Buah"; 
     } 

我把數據庫中的數據

 public void bacadatabase() 
     { 
      string sql = "select *from vanding_machine"; 
      server = "localhost"; 
      database = "db_s2u"; 
      uid = "root"; 
      password = ""; 

      string connString = "SERVER=" + server + ";" + " DATABASE=" + database + ";" + " UID=" + uid + ";" + " PASSWORD=" + password + ";"; //conek SQL 
      MySqlConnection conn = new MySqlConnection(connString); 


      conn.Open(); 
      //MessageBox.Show("Koneksi Berhasil"); 

      //command 
      MySqlCommand cmd = new MySqlCommand(sql, conn); 

      //reader 
      MySqlDataReader dataReader = cmd.ExecuteReader(); 

      while (dataReader.Read()) 
      { 
       produk11 = dataReader["produk1"].ToString(); 
       produk22 = dataReader["produk2"].ToString(); 
       produk33 = dataReader["produk3"].ToString(); 
      } 


      dataReader.Close(); 
      conn.Close(); 

     } 

當我點擊按鈕的數據將被輸入到數據庫和變量的原因該節目將自動更新

 private void button9_Click(object sender, EventArgs e) 
     { 

      server = "localhost"; 
      database = "db_s2u"; 
      uid = "root"; 
      password = ""; 

      string connString = "SERVER=" + server + ";" + " DATABASE=" + database + ";" + " UID=" + uid + ";" + " PASSWORD=" + password + ";"; //conek SQL 
      MySqlConnection conn = new MySqlConnection(connString); 


      conn.Open(); 
      //MessageBox.Show("Koneksi Berhasil"); 


      string sql = "update vanding_machine set produk1 = @produk111;"; 

      MySqlCommand cmd = new MySqlCommand(sql, conn); 
      cmd.Parameters.Add(new MySqlParameter("@produk111", tb_produk1.Text)); 

      //close data reader 
      cmd.ExecuteNonQuery(); 

      //close connection 
      conn.Close(); 

     } 

     private void button8_Click(object sender, EventArgs e) 
     { 

     } 

     private void button7_Click(object sender, EventArgs e) 
     { 

     } 

     private void button4_Click(object sender, EventArgs e) 
     { 

     } 

     private void button2_Click_1(object sender, EventArgs e) 
     { 

     } 
    } 
} 

Answer 1

您將不得不創建計時器來檢查應用程序中是否更改了數據。數據庫不會指出有關任何變化的應用程序