以下这段代码为Login登录界面的代码:using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Data.Sql;
using System.Configuration;
namespace PictureManager
{
    public partial class Login : Form
    {
        public Login()
        {
            InitializeComponent();
        }        private void Login_Load(object sender, EventArgs e)
        {        }        private void btnLogin_Click(object sender, EventArgs e)
        {
            if (this.txtUserName.Text == "")
            {
                MessageBox.Show("用户名不能为空!", "错误");
            }
            else if (this.txtPassWord.Text == "")
            {
                MessageBox.Show("密码不能为空!", "错误");
            }     
            if (CheckUser() > 0)
            {
                PicManager pic = new PicManager();
                pic.Show();
                this.Hide();
            }
            else
            {
                MessageBox.Show("用户名或密码不正确");
            }        }
        public int CheckUser()
        {
            if (this.txtUserName.Text == "")
            {
                MessageBox.Show("用户名不能为空!", "错误");
            }
            else if (this.txtPassWord.Text == "")
            {
                MessageBox.Show("密码不能为空!", "错误");
            }
            string str = System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"];
            SqlConnection conn = new SqlConnection(str);
            SqlCommand cmd = new SqlCommand("Login", conn);            cmd.CommandType = CommandType.StoredProcedure;
            SqlParameter UserName = new SqlParameter("@username", SqlDbType.VarChar, 50);
            UserName.Value = this.txtUserName.Text;
            cmd.Parameters.Add(UserName);            SqlParameter PassWord = new SqlParameter("@pwd", SqlDbType.VarChar, 50);
            PassWord.Value = this.txtPassWord.Text;
            cmd.Parameters.Add(PassWord);            SqlParameter sp = new SqlParameter("@return", SqlDbType.Int, 4);            sp.Direction = ParameterDirection.Output;
            cmd.Parameters.Add(sp);            try
            {
                conn.Open();
                cmd.ExecuteNonQuery();
                conn.Close();
                int n = (int)(sp.Value);
                return n;
            }
            catch
            {
                return 0;
            }        }        private void btnCancel_Click(object sender, EventArgs e)
        {
            txtUserName.Text = "";
            txtPassWord.Text = "";
      }
    }
}
界面
但是就是登录不了,登录需要连接数据库里表的用户名和密码来验证。
又高手帮忙谢谢了。