这里我有三个变量，变量由数据库中的数据填充，并使用标签将其显示到屏幕上。 但是当我更改数据库中的数据时，变量不会自动更改。 我会尝试做的是创建一个变量，以便在数据库中的数据发生变化时自动更改。 但我不知道该怎么做，因为我是新手。
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();
}
我使用标签显示它
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";
}
我把数据库里的数据拿走了
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();
}
当我点击按钮时，数据将被输入数据库，节目中的变量将自动更新
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)
{
}
}
}
最佳答案
您必须创建计时器来检查应用程序中的数据是否已更改。数据库不会指向应用程序的任何更改
关于c# - 当数据库中的数据发生变化时更新变量，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/40604911/