c# - Querying data table to get particular row in C#

Question

I have data table which has columns namely Amount,StartDate. I am trying to get particular amount value from Amount based on StartDate.

My code is as follows:

DataTable dtt =_dstt.Tables[0];
var res = from r in dtt.AsEnumerable()
          where  r.Field("StartDate") == Convert.ToDateTime(drpStartYear.SelectedValue));
          select r.Field("Amount");

I am getting following error:

The type arguments for method 'System.Data.DataRowExtensions.Field(System.Data.DataRow, int)' cannot be inferred from the usage. Try specifying the type arguments explicitly.

_dsst is DataSet which I populate from database.

Is there better way to do it?

Answer 1

这样做

DataTable dtt =_dstt.Tables[0];
var res = from r in dtt.AsEnumerable()
where  r.Field<DateTime>("StartDate") == Convert.ToDateTime(drpStartYear.SelectedValue));
select r.Field<Double>("Amount");

您需要像这样指定列的 DataTyper.Field<YourType>("ColumnName")

Answer 2

var res = from r in dtt.AsEnumerable()
          where  r.Field<DateTime>("StartDate") == Convert.ToDateTime(drpStartYear.SelectedValue));
          select r.Field<double>("Amount");

Answer 3

DataTable dtt =_dstt.Tables[0];
var res = from r in dtt.AsEnumerable()
          where  r.Field<type>("StartDate") == Convert.ToDateTime(drpStartYear.SelectedValue));
          select r.Field<type>("Amount");

type in <> 将是您正在使用的争论类型