从DataTable中的DataRows中选择并提取值-C＃

Question

I have a method that accept these arguments:

public bool CalculateProvent(ArrayList UPs, 
                             ArrayList DateExtraction, 
                             DataTable SourceData

{

...
...
}

The SourceData datatable has this content (for example):

UP - DateExtraction - Energy1 - Energy2 - Consumption1 - Consumption2 - etc

with some values:

780 - 2011-11-12 14:00:00 - 30.50 - NULL - NULL - 12.00
780 - 2011-11-12 15:00:00 - 31.50 - NULL - 10 - 12.00
781 - 2011-11-12 14:00:00 - NULL - 6 - NULL - 12.00
...

I have to iterate this datatable based on the UPs and DataExtraction arraylist's to extract the needed field values (Energy1, etc.).

For example:

Decimal myEnergy1, myEnergy2, myConsumption1, myConsumption2

foreach(int up in UPs)
{
    foreach(DateTime myTime in DateExtraction)
  {

   // Here I have to select the correct row and extract my fields
  }

}

How can I select the correct values in this iteration?

Answer 1

I think something like this might be what you are looking for.

var q = from up in UPs.Cast<int>()
        from myTime in DateExtraction.Cast<DateTime>()
        join r in SourceData.AsEnumerable() on 
          new { r.Field<int>("UP"), r.Field<DateTime>("DateExtraction")} equals
          new { up, myTime }
        select new
        {
           Energy1 = r.Field<Decimal>("Energy1"),
           Energy2 = r.Field<Decimal>("Energy2")
        };

Answer 2

try this:

foreach(int up in UPs)
{
  foreach(DateTime myTime in DateExtraction)
  {
    DataRow[] myRows = SourceData.Select("UP=" + up + " AND DateExtraction='" + myTime.ToString() + "'");

    if(myRows != null && myRows.Length == 1)
    {
      // here is your row... myRows[0]
    }
  }
}

of course should be improved and pay attention to the myTime.ToString() format. surely this can also be done with nice and compact LINQ to DataSets