突然用参数值，不知道如何写登陆代码了。

突然用参数值，不知道怎么写登陆代码了。。。
第一次用参数写登陆代码。。。
首先是DAL层：

C# code

  public bool Login(UserModel um)         {             bool flag = false;             string sql = "select * from User where UserName=@username";             SqlParameter[] paras = new SqlParameter[]{              new SqlParameter("username",um.UserName),              new SqlParameter("userpwd",um.UserPwd),              new SqlParameter("departmentname",um.DepartMentName)             };             int res = sqlhelper.CheckLogin(sql,paras,CommandType.Text);             if (res > 0)             {                 flag = true;             }             return flag;         }

C# code

  public bool Login(UserModel um)         {             bool flag = false;             string sql = "select * from User where UserName=@username And userpwd=@userpwd And departmentname=@departmentname";             SqlParameter[] paras = new SqlParameter[]{              new SqlParameter("@username",um.UserName),              new SqlParameter("@userpwd",um.UserPwd),              new SqlParameter("@departmentname",um.DepartMentName)             };             int res = sqlhelper.CheckLogin(sql,paras,CommandType.Text);             if (res > 0)             {                 flag = true;             }             return flag;         }