做一个 有限制的登陆窗口

要求:

• 编写一个窗体，往Users表中添加一条数据
• UserName 不能为空，不能重复
• PassWord 两次密码，一致才行
• NickName 如果没填，自动填入“这家伙很懒”
• Sex 用单选按钮来让用户选择
• Birthday 生日
• Nation 下拉列表，显示所有民族的名称，默认选中一个
• 通过用户选择的民族名称 ，填入相应的民族编号
• 注册按钮，只要上面有一项未按照规定填写，那么注册按钮就不会将数据保存至数据库  

布局大概是这个样子。性别默认属性为true  生日用的datatimepiker  民族是comboBox  属性dropdownstyle修改为dropdownlist

 这是窗体代码，  每个控件的限制，和  事件 。

public partial class Form1 : Form
    {
        bool usernameisok = false; //判断用户名
        bool pwdisok = false;//判断密码

        public Form1()
        {
            InitializeComponent();

            //绑定民族信息
            List<UserNation> nlist = new UserNationData().SelectAll();

            comboBox1.DataSource = nlist;
            comboBox1.DisplayMember = "NationName";
            comboBox1.ValueMember = "NationCode";

        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (!usernameisok)
            {
                textBox1.BackColor = Color.Red;
            }
            else if (!pwdisok)
            {
                textBox2.BackColor = Color.Red;
                textBox3.BackColor = Color.Red;
            }
            else
            {
                Users u = new Users();
                u.UserName = textBox1.Text.Trim();
                u.PassWord = textBox2.Text;
                if (textBox4.Text.Trim().Length > 0)
                    u.NickName = textBox4.Text.Trim();
                else
                    u.NickName = "这家伙很懒";

                u.Sex = radioButton1.Checked;

                u.Birthday = dateTimePicker1.Value;

                u.Nation = comboBox1.SelectedValue.ToString();

                bool insertOK = new UsersData().InsertUser(u);
                if (insertOK)
                {
                    MessageBox.Show("注册成功！");
                }
                else
                {
                    MessageBox.Show("注册失败！服务器连接失败，请联系110！");
                }

            }
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            textBox1.BackColor = Color.White;
            //判断用户名
            string uname = textBox1.Text;
            if (uname.Trim().Length <= 0)
            {
                label_usernameMsg.Text = "用户名不能为空！";
                label_usernameMsg.ForeColor = Color.Red;
                usernameisok = false;
            }
            else
            {
                bool has = new UsersData().HasUserName(uname);

                if (has)
                {
                    label_usernameMsg.Text = "用户名已存在！";
                    label_usernameMsg.ForeColor = Color.Red;
                    usernameisok = false;
                }
                else
                {
                    label_usernameMsg.Text = "恭喜！用户名可以使用！";
                    label_usernameMsg.ForeColor = Color.Green;
                    usernameisok = true;
                }
            }
        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {
            textBox2.BackColor = Color.White;
            textBox3.BackColor = Color.White;

            if (textBox2.Text == textBox3.Text)
            {
                label_pwdError.Text = "正确！";
                label_pwdError.ForeColor = Color.Green;
                pwdisok = true;
            }
            else
            {
                label_pwdError.Text = "两次密码不一致";
                label_pwdError.ForeColor = Color.Red;
                pwdisok = false;
            }
        }

    }
}

这是用了两个数据访问类   

代码使用了里面的方法

 public class UserNationData
    {
        SqlConnection conn = null;
        SqlCommand cmd = null;

        public UserNationData()
        {
            conn = new SqlConnection("server=.;database=wowowo;user=sa;pwd=123");
            cmd = conn.CreateCommand();
        }

        public List<UserNation> SelectAll()
        {
            List<UserNation> list = new List<UserNation>();

            cmd.CommandText = "select *from UserNation";
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                UserNation un = new UserNation();
                un.NationCode = dr[0].ToString();
                un.NationName = dr[1].ToString();
                list.Add(un);
            }
            conn.Close();
            return list;
        }



    }

 public class UsersData
    {
        SqlConnection conn = null;
        SqlCommand cmd = null;

        public UsersData()
        {
            conn = new SqlConnection("server=.;database=wowowo;user=sa;pwd=123");
            cmd = conn.CreateCommand();
        }


        public List<Users> SelectAll()
        {
            List<Users> list = new List<Users>();
            cmd.CommandText = "select *from Users";

            try
            {
                conn.Open();
                SqlDataReader dr = cmd.ExecuteReader();
                while (dr.Read())
                {
                    Users u = new Users();
                    u.Ids = Convert.ToInt32(dr["ids"]);
                    u.UserName = dr["UserName"].ToString();
                    u.PassWord = dr["PassWord"].ToString();
                    u.NickName = dr["NickName"].ToString();
                    u.Sex = Convert.ToBoolean(dr["Sex"]);
                    u.Birthday = Convert.ToDateTime(dr["Birthday"]);
                    u.Nation = dr["Nation"].ToString();

                    list.Add(u);
                }
            }
            catch
            {
                Users u = new Users();
                u.UserName = "服务器连接失败！";
                u.PassWord = "UserError500";
                list.Add(u);
            }
            finally
            {
                conn.Close();
            }
            return list;
        }

        public bool HasUserName(string uname)
        {
            bool b = false;

            cmd.CommandText = "select *from Users where UserName = @a";
            cmd.Parameters.Clear();
            cmd.Parameters.AddWithValue("@a", uname);
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            if (dr.HasRows)
            {
                b = true;
            }
            conn.Close();
            return b;
        }

        public bool InsertUser(Users u)
        {
            bool ok = false;

            cmd.CommandText = "insert into Users values(@a,@b,@c,@d,@e,@f);";
            cmd.Parameters.Clear();
            cmd.Parameters.Add("@a", u.UserName);
            cmd.Parameters.Add("@b", u.PassWord);
            cmd.Parameters.Add("@c", u.NickName);
            cmd.Parameters.Add("@d", u.Sex);
            cmd.Parameters.Add("@e", u.Birthday);
            cmd.Parameters.Add("@f", u.Nation);
            try
            {
                conn.Open();
                int a = cmd.ExecuteNonQuery();
                if (a > 0)
                {
                    ok = true;
                }
            }
            catch { ok = false; }
            conn.Close();
            return ok;
        }


    }