//Function: initialize a concrete user, return it as use of this session, if the user is valid
//Paramaters:
//Return: concrete user type, (Customer or Manager)
// null when the user is invalid
//用户身份验证，根据名字密码查数据库，合法的话，返回出manager或者customer
//不合法返回NUll
public static User Login(string pName, string pPwd)
{
User user = null;
DataContextDataContext dc = new DataContextDataContext();
bool? isValid = false;
ISingleResult<is_valid_userResult> rs = dc.is_valid_user(pName, pPwd, ref isValid);
if (isValid == true)
{
foreach (is_valid_userResult s in rs)
{
if (s.type == 1)
{
user = new Customer(s.name, s.pwd, s.mail);
}
else if (s.type == 2)
{
user = new Manager(s.name, s.pwd, s.mail);
}
else
{ }
}
}
else //invalid
{}
return user;
}