Question

我是C＃的新手。我创建了登录界面。我无法检查用户名和密码。这是我的代码。任何人都可以帮我。谢谢。请不要犹豫，复制代码。

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Windows.Forms;
 using System.Data.SqlClient;
 using System.Data.Sql;

    namespace Voting_Editor_Tool
    {
       public partial class Form1 : Form
     {
         SqlConnection cn;
         public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {


    }

    private void button2_Click(object sender, EventArgs e)
    {
        Application.Exit();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        string username = txtusername.Text;
        string password = txtpassword.Text;

        if (ValidateUserNamePassword(username, password))
        {
            // move to next form or do whatever you need to do after a successfull login
        }
        else
        {
            MessageBox.Show("Invalid user name or password", "Invalid Login");
            return;
        }
    }
    public bool ValidateUserNamePassword(string _username, string _password)
    {
                  //  string connectionString = "Data Source=[servername];Initial                           Catalog=[databaseName];User ID=[Admin Login];Password=[Admin Password];";

   using (SqlConnection cn= new SqlConnection(@"User ID=sa;Password=password123;Initial Catalog=dish_tv;Data Source=ENMEDIA-CCDDFE5\ENMEDIA"));
   {
      SqlCommand cmd = new SqlCommand();
      cmd.Connection = cn;
      cmd.CommandType = CommandType.StoredProcedure;
      cmd.CommandText = "tsp_GetUserNameAndPassword";

      SqlParameterCollection sqlParams = cmd.Parameters;
      sqlParams.AddWithValue("@username", _username);
      sqlParams.AddWithValue("@password", _password);

      cn.Open();
      SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.SingleRow);
      if (dr.Read())
      {
            // this will return true if a row matching the username and password is found.
            // this means that the user's input is valid
            return true;
      }
      else
      {
            return false;
       }

      dr.Close();
      cn.Close();
   }
      }


    }
  }

Answer 1

您在using语句的末尾有一个分号，因此终止使用。删除分号，它将起作用。

Answer 2

删除你的using子句并将那段代码放入Try .. catch块。捕获异常对象并读取其stacktrace。检查连接字符串是否有任何拼写错误。这应该给你提供更多的调试细节，而不是像“对象引用没有设置为对象的实例”这样的通用错误

SQL连接对象的空引用

2 个答案: