c#+SqlServer 用户注册、登录验证、操作

用户注册

        //注册用户验证
        public void regist()
        {
            string userName = Txt_userName.Text.Trim();
            string passWord = Txt_passWord.Text.Trim();

            try
            {
                if (userName != "" && passWord != "")
                {
                    SqlConnection cn = new SqlConnection(cnstr);
                    cn.Open();

                    string sql = "insert into Table_login values('" + userName + "','" + passWord + "')";
                    SqlCommand cmd = new SqlCommand(sql, cn);
                    int count = cmd.ExecuteNonQuery();
                    if (count > 0)
                    {
                        MessageBox.Show("注册成功！", "提示");
                        resetTxt();
                    }
                    else
                        MessageBox.Show("注册失败", "提示");
                    cn.Dispose();
                }
                else
                {
                    MessageBox.Show("用户名不能为空，且两次密码输入必须一致！", "提示");
                }
            }
            catch (Exception e1)
            {
                MessageBox.Show(e1.Message, "提示");
            }
        }

        //注册的数据库操作
        private void Btn_register_Click(object sender, EventArgs e)
        {
            string userName = Txt_userName.Text.Trim();
            SqlConnection cn = new SqlConnection(cnstr);
            cn.Open();
            string sql = "select count(*) from Table_login where userName='" + userName + "'";
            SqlCommand cmd = new SqlCommand(sql, cn);
            int count = (int)cmd.ExecuteScalar();
            if (count > 0)
            {
                MessageBox.Show("注册失败,该用户已存在！", "提示");
            }
            else
            {
                regist();
            }
            cn.Dispose();
            cn.Close();
        }

        //重置用户名、密码的方法
        public void resetTxt()
        {
            this.Txt_userName.Text = "";
            this.Txt_passWord.Text = "";
        }

登录验证

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.Sql;
using System.Data.SqlClient;

namespace Login_Form
{
    public partial class Login_Form : Form
    {
        public Login_Form()
        {
            InitializeComponent();
        }
        public static String cnstr = "Integrated Security=SSPI;Persist Security Info=False;User ID=sa;Initial Catalog=Db_net;Data Source=.";
        //登录验证
        private void login_Btn_Click(object sender, EventArgs e)
        {
            string userName = userName_Txt.Text.Trim();
            string passWord = pwd_Txt.Text.Trim();
            try
            {
                SqlConnection cn = new SqlConnection(cnstr);
                cn.Open();

                string sql = "select count(*) from UserTable where userName='" + userName + "'and passWord='" + passWord + "'";
                SqlCommand cmd = new SqlCommand(sql, cn);
                int count = (int)cmd.ExecuteScalar();
                if (count > 0)
                {
                    MessageBox.Show("登录成功", "提示");
                    main_Form m1 = new main_Form();
                    m1.ShowDialog();
                    this.Hide();
                }
                else
                {
                    MessageBox.Show("用户名或密码错误", "提示");
                }
            }
            catch (Exception e1)
            {
                MessageBox.Show("'"+ e1 +"'", "提示");
            }
        }
        //重置用户名、密码的方法
        public void resetTxt()
        {
            this.userName_Txt.Text = "";
            this.pwd_Txt.Text = "";
        }
        //重置用户名、密码
        private void reset_Btn_Click(object sender, EventArgs e)
        {
            resetTxt();
        }
    }
}