1、创建Company数据库中的UserInfo表，其中字段包括ID、UserName、UserPassword、UserAge、UserSex

USE Company
CREATE TABLE UserInfo
(
ID INT NOT NULL PRIMARY KEY IDENTITY(1,1),
UserName NVARCHAR(32),
UserPassword NVARCHAR(32),
UserAge INT NOT NULL DEFAULT(18),
UserSex NCHAR(8)
)

2、数据库连接字符串存放在应用程序的配置文件中，通过configurationManager类的ConnectionStrings属性读取配置文件中XML格式的键值对，从而拿到数据库连接字符串。

引入System.Configuration类库，导入ConfigurationManager类的命名空间System.Configuration。

using System.Configuration;

创建数据库连接字符串

string strCon = ConfigurationManager.ConnectionStrings["SQLString"].ConnectionString;

3、主界面注册按钮单击弹出注册界面

        private void RegistButton_Click(object sender, EventArgs e)
        {
            RegistForm regFrm = new RegistForm();
            regFrm.Show();
        }

弹出注册界面.jpg

注册界面代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Configuration;
using System.Data.SqlClient;

namespace UserFormExample
{
    public partial class RegistForm : Form
    {
        public RegistForm()
        {
            InitializeComponent();
        }

        //注册按钮
        private void RegistButton_Click(object sender, EventArgs e)
        {
            //调用CheckFrmTxt函数简单校验数据
            if (!CheckFrmTxt())
            {
                return;
            }
            //通过ConfigurationManager类从配置文件中读取数据库连接字符串
            string strCon = ConfigurationManager.ConnectionStrings["SQLString"].ConnectionString;
            //创建数据库连接对象
            using (SqlConnection connect = new SqlConnection(strCon))
            {
                //打开数据库
                connect.Open();
                //构建SQL命令对象
                using (SqlCommand cmd = connect.CreateCommand())
                {
                    //构建SQL插入数据命令
                    string strSql = string.Format($"insert into UserInfo(UserName,UserPassword,UserAge,UserSex)values('{this.UserNameTextBox.Text}','{this.PasswordTextBox.Text}','{int.Parse(this.AgeTextBox.Text)}','{this.SexTextBox.Text}')");
                    cmd.CommandText = strSql;
                    //执行非查询SQL命令
                    cmd.ExecuteNonQuery();
                }
            }
            MessageBox.Show("注册成功");
        }
        private bool CheckFrmTxt()
        {
            if (string.IsNullOrEmpty(this.UserNameTextBox.Text.Trim()))
            {
                MessageBox.Show("用户名不能为空！");
                return false;
            }
            return true;
        }
    }
}

注册.jpg

4、登录界面（主界面）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.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Configuration;

namespace UserFormExample
{
    public partial class MainForm : Form
    {
        public MainForm()
        {
            InitializeComponent();
        }

        private void LoginButton_Click(object sender, EventArgs e)
        {
            //简单校验数据
            if (string.IsNullOrEmpty(this.UserNameTextBox.Text.Trim())||string.IsNullOrEmpty(this.PasswordTextBox.Text.Trim()))
            {
                MessageBox.Show("请输入正确的用户名和密码");
                return;
            }
            //构建数据库连接对象
            string strCon = ConfigurationManager.ConnectionStrings["SQLString"].ConnectionString;
            using (SqlConnection connect = new SqlConnection(strCon))
            {
                //打开数据库
                connect.Open();
                //构建SQL命令对象
                using (SqlCommand cmd = connect.CreateCommand())
                {
                    //构建查询SQL命令
                    string strSql = string.Format($"select count(1) from UserInfo where UserName='{this.UserNameTextBox.Text}' and UserPassword='{this.PasswordTextBox.Text}'");
                    cmd.CommandText = strSql;
                    //执行查询命令，返回第一行第一列的值为Object类型
                    object result = cmd.ExecuteScalar();
                    int rows = int.Parse(result.ToString());
                    if (rows>=1)
                    {
                        MessageBox.Show("登录成功");
                    }
                    else
                    {
                        MessageBox.Show("登录失败");
                    }
                }
            }
        }

        private void RegistButton_Click(object sender, EventArgs e)
        {
            RegistForm regFrm = new RegistForm();
            regFrm.Show();
        }
    }
}

登录.jpg