用户登录模块--代码

界面：

代码（账户：100001  密码：200002）：

        /// <summary>
        /// 登陆事件
        /// </summary>
        private void btn_OK_Click(object sender, EventArgs e)
        {
            if (this.txt_Pwd.Text.Trim() == "" && this.txt_User.Text.Trim() == "")
            {
                MessageBox.Show("不能为空！", "提示");
            }
            else
            {
                int i = 0;

                string sql = string.Empty;

                SqlParameter[] para = null;

                SqlHelper shl = new SqlHelper();

                sql = "select * from UserLogin where UserAccount = @User";

                para = new SqlParameter[]
                {
                    new SqlParameter("@User", this.txt_User.Text.Trim())
                };

                i = shl.ExecuteScalar(sql, para, CommandType.Text);

                if (i == 1)
                {
            sql = "select * from UserLogin where UserAccount = @User and UserPwd = @Pwd";

                    para = new SqlParameter[]
                    {
                        new SqlParameter("@User", this.txt_User.Text.Trim()),
                        new SqlParameter("@Pwd", this.txt_Pwd.Text.Trim())
                    };

                    i = shl.ExecuteScalar(sql, para, CommandType.Text);

                    if (i != 1)
                    {
                        MessageBox.Show("登陆失败，请检查账户和密码！", "提示");
                    }
                    else
                    {
                        Temp Tm = new Temp();

                        Tm.Show();

                        this.Close();
                    }
                }
                else
                {
                    MessageBox.Show("账户不存在，请重新输入！", "提示");
                }
            }
        }

完成。