在 C# 中使用 linq to datatable 的 SQL 查询的等效代码是什么？

Question

这是我在 T-SQL 中的查询，我想在 C# 中使用 linq to datatable 做确切的事情。

select
    @found = MorningIsWorking, 
    @Sh_startTime = MorningStart, 
    @Sh_endTime = MorningEnd 
from t 
where 
    t.plannum = @pn and 
    t.Date = @datepart and 
    (@timepart between MorningStart and MorningEnd)

其中MorningIsWorking是布尔值， MorningStart和MorningEnd ， @timepart是时间， @datepart是 DateTime

已编辑

这就是我所做的，但我不知道它是否正确以及如何在变量中获取所需的值。

var res = from row in dt.AsEnumerable()
                  where row.Field<string>("plannum") == "995" &
                  row.Field<DateTime>("date") == Convert.ToDateTime("2016-08-25 10:25:00").Date &
                  Convert.ToDateTime(timepart) >= row.Field<DateTime>("MorningStart") &
                  Convert.ToDateTime(timepart) < row.Field<DateTime>("MorningEnd")
                  select row;

Answer 1

根据您提供的信息，我相信这是您要完成的工作的 LINQ。

DateTime timepart = new DateTime(2017,2,7);
DateTime datepart = new DateTime(2016, 8, 25, 10, 25, 0);
string plannum = "995";

using (DataSet1 dt = new DataSet1())
{
     var res = from row in dt.t.AsEnumerable()
          where row.plannum == plannum &&
          row.Date == datepart &&
          timepart >= row.MorningStart &&
          timepart < row.MorningEnd
          select row;

     foreach (var row in res)
     {
          var found = row.MorningIsWorking;
          var shStartTime = row.MorningStart;
          var shEndTime = row.MorningEnd;
     }
}

或者，如果您只期望返回一行，则可以按如下方式省略 foreach 循环。

DateTime timepart = new DateTime(2017,2,7);
DateTime datepart = new DateTime(2016, 8, 25, 10, 25, 0);
string plannum = "995";

using (DataSet1 dt = new DataSet1())
{
     var res = (from row in dt.t.AsEnumerable()
          where row.plannum == plannum &&
          row.Date == datepart &&
          timepart >= row.MorningStart &&
          timepart < row.MorningEnd
          select row).Single();


     var found = res.MorningIsWorking;
     var shStartTime = res.MorningStart;
     var shEndTime = res.MorningEnd;
}

Answer 2

我使用了这个代码，它对我有用。

DataRow row = dt.AsEnumerable().FirstOrDefault
            (r => (DateTime)r["date"] == timeToCompare.Date
            & r.Field<string>("plannum") == "0995" &
            tp >= r.Field<TimeSpan>("MorningStart") &
            tp < r.Field<TimeSpan>("MorningEnd"));

然后使用它来获取值：

sh_starttime = row["MorningStart"].ToString();