C# 如何将日期时间仅定为日期

这是我的看法

SELECT        AmenityValidDatesPriceID, AmenityID, AmenityValidDatesFrom, AmenityValidDatesTo, AddedDate, LastModifyDate, AddedUser, LastModifyUser, 
                         IsDeleted
FROM            dbo.DataManagement_Hotels_Amenities_AmenityValidDatesPrice
WHERE        (IsDeleted = 0)

它返回我amentityvaliddatesfrom，amentityvaliddatesto作为datetime

在前端，我只需要约会

    public List<BLL.Entities.DataManagement_Hotels_Amenities_AmenityValidDatesPrice> SelectByAmenityID(int ID)
            {
                DAL.DynamicSearchViewDataContext Viewcontext = new DAL.DynamicSearchViewDataContext();
                DAL.SelectSectionDataContext SpContext = new DAL.SelectSectionDataContext();
                var Query = (from car in Viewcontext.View_DataManagement_Hotel_Amenities_Dates
                             where car.AmenityID.Equals(ID)
                             select new BLL.Entities.DataManagement_Hotels_Amenities_AmenityValidDatesPrice
                             {
                                 AmenityID = (int)car.AmenityID,
                                 //AmenityValidDatesFrom = (DateTime)car.AmenityValidDatesFrom,
                                 //AmenityValidDatesTo = (DateTime)car.AmenityValidDatesTo

                                 AmenityValidDatesFrom = ((DateTime)car.AmenityValidDatesFrom).Date,
                                 AmenityValidDatesTo = ((DateTime)car.AmenityValidDatesTo).Date


                             }).ToList<BLL.Entities.DataManagement_Hotels_Amenities_AmenityValidDatesPrice>();
                return Query;

            }

public List selectbyamendityid（int-ID）
{
DAL.DynamicSearchViewDataContext Viewcontext=新建DAL.DynamicSearchViewDataContext（）；
DAL.SelectSectionDataContext SpContext=新建DAL.SelectSectionDataContext（）；
var Query=（来自Viewcontext.View\数据管理\酒店\设施\日期中的汽车
其中汽车修正ID等于（ID）
选择新的BLL.Entities.DataManagement\u Hotels\u communications\u amendityValidDatesPrice
{
修正项ID=（int）car.amentityID，
//AmentityValidDatesFrom=（日期时间）car.AmentityValidDatesFrom，
//AmentityValidDataTesto=（日期时间）car.AmentityValidDataTesto
amendityValidDatesFrom=（（日期时间）car.amendityValidDatesFrom）.日期，
amendityvaliddatesto=（（日期时间）car.amendityvaliddatesto.Date
}).ToList（）；
返回查询；
}

这是我的密码

它给

隐式转换错误

---

请更改您的视图，如下所示：

SELECT  AmenityValidDatesPriceID,
        AmenityID,
        CONVERT(VARCHAR, AmenityValidDatesFrom,101) AS AmenityValidDatesFrom,
        CONVERT(VARCHAR, AmenityValidDatesTo,101) AS AmenityValidDatesTo,
        CONVERT(VARCHAR, AddedDate,101) AS AddedDate,
        CONVERT(VARCHAR, LastModifyDate,101) AS LastModifyDate,
        AddedUser,
        LastModifyUser,
        IsDeleted
FROM    dbo.DataManagement_Hotels_Amenities_AmenityValidDatesPrice
WHERE   IsDeleted = 0

它应该会起作用

更新：

需要进行空检查

public List<BLL.Entities.DataManagement_Hotels_Amenities_AmenityValidDatesPrice> SelectByAmenityID(int ID)
{
    DAL.DynamicSearchViewDataContext Viewcontext = new DAL.DynamicSearchViewDataContext();
    DAL.SelectSectionDataContext SpContext = new DAL.SelectSectionDataContext();
    var Query = (from car in Viewcontext.View_DataManagement_Hotel_Amenities_Dates
                 where car.AmenityID.Equals(ID)
                 select new BLL.Entities.DataManagement_Hotels_Amenities_AmenityValidDatesPrice
                 {
                     AmenityID = (int)car.AmenityID,
                     if (car.AmenityValidDatesFrom != null && car.AmenityValidDatesFrom.ToString() !=  "")
                     {
                        AmenityValidDatesFrom = car.AmenityValidDatesFrom.Date
                     },
                     if (car.AmenityValidDatesTo != null && car.AmenityValidDatesTo.ToString() !=  "")
                     {
                        AmenityValidDatesTo = car.AmenityValidDatesTo.Date
                     }
                 }).ToList<BLL.Entities.DataManagement_Hotels_Amenities_AmenityValidDatesPrice>();
    return Query;
}

public List selectbyamendityid（int-ID）
{
DAL.DynamicSearchViewDataContext Viewcontext=新建DAL.DynamicSearchViewDataContext（）；
DAL.SelectSectionDataContext SpContext=新建DAL.SelectSectionDataContext（）；
var Query=（来自Viewcontext.View\数据管理\酒店\设施\日期中的汽车
其中汽车修正ID等于（ID）
选择新的BLL.Entities.DataManagement\u Hotels\u communications\u amendityValidDatesPrice
{
修正项ID=（int）car.amentityID，
if（car.amendityvaliddatesfrom！=null&&car.amendityvaliddatesfrom.ToString（）！=“”）
{
amendityValidDatesFrom=car.amendityValidDatesFrom.Date
},
if（car.amendityvaliddatesto！=null&&car.amendityvaliddatesto.ToString（）！=“”）
{
amendityvaliddatesto=car.amendityvaliddatesto.Date
}
}).ToList（）；
返回查询；
}

试试这个

SELECT  AmenityValidDatesPriceID ,
        AmenityID ,
        CONVERT(VARCHAR(10), AmenityValidDatesFrom, 103) AS AmenityValidDatesFrom ,
        CONVERT(VARCHAR(10), AmenityValidDatesTo, 103) AS AmenityValidDatesTo ,
        CONVERT(VARCHAR(10), AddedDate, 103) AS AddedDate ,
        CONVERT(VARCHAR(10), LastModifyDate, 103) AS LastModifyDate ,
        AddedUser ,
        LastModifyUser ,
        IsDeleted
FROM    dbo.DataManagement_Hotels_Amenities_AmenityValidDatesPrice
WHERE   IsDeleted = 0

---

它将以“dd/mm/yyyy”格式给出日期。如果要以“mm/dd/yyyy”格式获取日期，请使用101而不是103

使用此视图保留

DATETIME

数据类型，同时删除时间部分：

SELECT  AmenityValidDatesPriceID ,
        AmenityID ,

        DATEADD(D, 0, DATEDIFF(D, 0, AmenityValidDatesFrom)) AS AmenityValidDatesFrom
        DATEADD(D, 0, DATEDIFF(D, 0, AmenityValidDatesTo)) AS AmenityValidDatesTo
        DATEADD(D, 0, DATEDIFF(D, 0, AddedDate)) AS AddedDate
        DATEADD(D, 0, DATEDIFF(D, 0, LastModifyDate)) AS LastModifyDate

        AddedUser ,
        LastModifyUser ,
        IsDeleted
FROM    dbo.DataManagement_Hotels_Amenities_AmenityValidDatesPrice
WHERE   IsDeleted = 0

---

你的问题是什么？您的消息错误是什么？您使用的是sql server还是其他？可能与数据类型是什么

car重复。是否从
修改验证数据？当您得到错误时，它的值是什么？参数“value”的类型错误。应为“System.DateTime”。实际的'System.Nullable'1[System.DateTime]'。我遇到此错误所有日期列中是否有空单元格或空值单元格？如果有空，则只有amendityValidDatesFrom=（（DateTime）car.amendityValidDatesFrom）.日期，amendityValidDatesTo=（（DateTime）car.amendityValidDatesTo）.日期，这两条语句将给您错误。我修改了视图。当我再次尝试获取数据时，代码中显示此错误，参数“value”的类型错误。应为“System.DateTime”。实际的“System.Nullable`1[System.DateTime]”。这将允许可为Null的类型：
car.AmentityValidDateFrom.GetValueOrDefault（）.Date