Nullable<System.DateTime>日期格式转换（转载）

一、问题

　1、html页面中时间显示出错，数据库中时间是正确的。

原因：没有把DateTime转成String类型。

　2、在C#中，发现不能直接使用ToString("yyyy-MM-dd HH:mm")这样的格式进行日期格式转换。

原因：在DB中，字段设置为Nullable<System.DateTime>，是可空的DateTime类型。

二、解决方案

　　if (user.BirthDate.HasValue)
　　{
　　　　userInfo.BirthDate = user.BirthDate.Value.ToString("yyyy-MM-dd");
　　}else
　　{
　　　　userInfo.BirthDate = string.Empty;
　　}

三、完整案例

public UserInfo GetUserNoPasswordByUserName(string userName)
{
     
    var user= db.T_User.Select(d => new  { Address = d.Address, BirthDate = d.BirthDate, Company = d.Company, Phone = d.Phone, RealName = d.RealName, TelPhone = d.TelPhone, TypeID = d.TypeID, UserID = d.UserID, UserName = d.UserName, UserStatus = d.UserStatus }).Where(d => d.UserName == userName).SingleOrDefault();
    UserInfo userInfo = new UserInfo();
    userInfo.Address = user.Address;
    if (user.BirthDate.HasValue)
    {
        userInfo.BirthDate =  user.BirthDate.Value.ToString("yyyy-MM-dd");
    }else
    {
        userInfo.BirthDate = string.Empty;
    }
    userInfo.Company = user.Company;
    userInfo.Phone = user.Phone;
    userInfo.RealName = user.RealName;
    userInfo.TelPhone = user.TelPhone;
    userInfo.TypeID = user.TypeID;
    userInfo.UserID = user.UserID;
    userInfo.UserName = user.UserName;
    userInfo.UserStatus = user.UserStatus;
  
    return userInfo;
 
}

//自定义视图数据类   
 public class UserInfo
    {
        public int UserID { get; set; }
        public string UserName { get; set; }
        public Nullable<short> TypeID { get; set; }
        public short UserStatus { get; set; }
       // public string Password { get; set; }
        public string RealName { get; set; }
        public string Company { get; set; }
        public string BirthDate { get; set; }
        public string Phone { get; set; }
        public string TelPhone { get; set; }
        public string Address { get; set; }
    }

//数据实体类  
public partial class T_User
 {
  
     public int UserID { get; set; }
     public string UserName { get; set; }
     public Nullable<short> TypeID { get; set; }
     public short UserStatus { get; set; }
     public string Password { get; set; }
     public string RealName { get; set; }
     public string Company { get; set; }
     public Nullable<System.DateTime> BirthDate { get; set; }
     public string Phone { get; set; }
     public string TelPhone { get; set; }
     public string Address { get; set; }
 
 }