如何从数据库中检索数据并将其显示在标签上 [英] How to retrieve data from database and display it on label

问题描述

我正在使用幸运抽奖系统的注册页面。因此，注册过程是用户需要使用USB条形码扫描器扫描他们的条形码。我坚持使用用户扫描后无法检查数据库上的员工ID或输入文本框的那部分。我还希望在扫描条形码后显示员工姓名。任何人都可以给我一些想法/解决方案。



我尝试过：



以下是我的代码：

I'm working on the Registration page for Lucky Draw system.So the process for registration is user need to scan their barcode using usb barcode scanner. I stuck on that part which i cannot check the employee id on database after user scan or type in the textbox. I also want to display the employee name after scan the barcode.Can anyone give me some ideas/solution.

What I have tried:

Below are my code:

using System;  
using System.Collections.Generic;  
using System.Data;  
using System.Data.SqlClient;  
using System.IO;  
using System.Linq;  
using System.Web;  
using System.Web.UI;  
using System.Web.UI.WebControls;
public partial class Attendance : System.Web.UI.Page  
{  
    SqlCommand cmd = new SqlCommand();  
    SqlConnection con = new SqlConnection();  
    string str;  
    private string connectionString;  
  
    protected void Page_Load(object sender, EventArgs e)  
    {  
        con.ConnectionString = @"Data Source= (LocalDB)\MSSQLLocalDB; AttachDbFilename =   
          C:\Users\Nor  Asyraf  Mohd No\source\repos\LuckyDraw\LuckyDraw\App_Data\ticket.mdf;   
            Integrated Security = True";
        txtText.Focus();  
    }  
  
    protected void btnSave_Click(object sender, EventArgs e)  
    {  
        idcheck();  
        using (SqlConnection connection = new SqlConnection(connectionString))  
        {  
            using (SqlCommand command = connection.CreateCommand())  
            {  
                command.CommandText = "UPDATE EMPLOYEES SET Attendance = 'Present' WHERE EMP_ID = @id";  
                command.Parameters.AddWithValue("@id", txtText.Text);  
                connection.Open();  
  
                command.ExecuteNonQuery();  
  
                connection.Close();  
            }  
        }
    }  
  
public void idcheck()  
        {
        string query = "select EMP_ID from EMPLOYEES where EMP_ID='" + txtText.Text + "'";  
        SqlDataAdapter ada = new SqlDataAdapter(query, con);  
        DataTable dt = new DataTable();  
        ada.Fill(dt);  
        if (dt.Rows.Count > 0)  
        {  
            lblError.Text = dt.Rows[0]["EMP_NAME"].ToString();  
        }  
    }
    protected void Button1_Click1(object sender, EventArgs e)  
    {  
        Response.Redirect("Default.aspx");  
    }  
}

推荐答案

考虑到您的ID列是整数，那么您必须更正这些行

从EMPLOYEES中选择EMP_ID，其中EMP_ID ='+ txtText.Text +';



as从EMPLOYEES中选择EMP_ID，其中EMP_ID =+ txtText.Text +;删除单引号。

Considering your ID column is interger then you have to correct these line
"select EMP_ID from EMPLOYEES where EMP_ID='" + txtText.Text + "'"; "

as "select EMP_ID from EMPLOYEES where EMP_ID= " + txtText.Text + " "; " remove single quotes.

在select查询中添加EMP_NAME，如果EMP_ID是整数，则从where where中删除单引号

add EMP_NAME in select query and if EMP_ID is integer remove single quotes from where condition

从您的数据库表中执行SqlCommand字符串select *

尝试使用

datareader = cmd.ExecuteReader（）执行并从数据库中读取数据，如

if（datareader.Read（））

label.InnerText = datareader [EmpID]。ToString（）;



这里我使用< label>标签代替< asp：label>标签....它适用于我尝试这个

Execute the SqlCommand string select * from the database table of yours
Try to execute with the
datareader = cmd.ExecuteReader() and read the data from the database like
if(datareader.Read())
label.InnerText = datareader["EmpID"].ToString();

Here i use <label> tag instead of <asp:label> tag.... It worked for me try this

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