public partial class FlightInf : INotifyPropertyChanging, INotifyPropertyChanged
{
private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);
private int _FlightID;
private string _OriginCH;
private string _OriginEN;
private string _DestinationCH;
private string _DestinationEN;
private string _FlightNum;
private System.Nullable<int> _Date;
private System.Nullable<int> _StartTimeHour;
private System.Nullable<int> _StartTimeMinute;
private System.Nullable<int> _EndTimeHour;
private System.Nullable<int> _EndTimeMinute;
public FlightInf()
{
OnCreated();
}
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_FlightID", DbType="Int NOT NULL", IsPrimaryKey=true)]
public int FlightID
{
get
{
return this._FlightID;
}
set
{
if ((this._FlightID != value))
{
this.OnFlightIDChanging(value);
this.SendPropertyChanging();
this._FlightID = value;
this.SendPropertyChanged("FlightID");
this.OnFlightIDChanged();
}
}
}
...
以上是定义的从数据库映射到DataContext的实体类。
以下使用linq对数据库表进行访问:DataContext ctx = new DataContext(@"server=*...");
Table<FlightInf> flightnum = ctx.GetTable<FlightInf>();
var aaa = from c in flightnum where c.FlightID.Equals(12) select c;我的问题是:
如何对aaa得到的数据内容进行操作?比如我想得到某一个字段的值。急切求指导
c# linq to sqlc#
foreach(var a in aaa)
{
s=a.FlightID;
}还有就是这句话:Table<FlightInf> flightnum = ctx.GetTable<FlightInf>();如果我的ctx对应的数据库里有上千万条记录的话,这样flightnum应该会占用很多的内存吧,我如果只是想选择几条记录,如何做效率会高一点?
Table<FlightInf> flightnum = ctx.GetTable<FlightInf>();
var aaa = from c in flightnum
where c.FlightID.Equals(12)
select new FlightInf
{
FlightUD=c.ID,
.......
};或者List<FlightInf> aaa = (from c in flightnum
where c.FlightID.Equals(12)
select new FlightInf
{
FlightUD=c.ID,
.......
}).ToList();
aaa你还不会操作吗??
List<FlightInf> 这个你不会操作???
Table<FlightInf> flightnum = ctx.GetTable<FlightInf>();
//select * from FlightInf where FlightID=12
var aaa = from c in flightnum where c.FlightID.Equals(12) select c;
//select OriginCH from FlightInf where FlightID=12
var query = from c in flightnum where c.FlightID.Equals(12) select c.OriginCH ;
////select OriginCH,OriginEN from FlightInf where FlightID=12
var result = from c in flightnum where c.FlightID.Equals(12) select new{ c.OriginCH,c.OriginEN };
List<FlightInf> 这个你不会操作???谢谢,这个我会了。