LINQ to Datatable RSS

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  medivo

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  LINQ to Datatable

  Apr 07, 2012 09:58 PM|LINK

  Hi guys,

  Can sombody please help me? I have datatble called DT with columns : kodId,kodO,RO,RD,Text and I need to select all Texts from rows with specific kodId and with with specific range between RO and RD. I have tried this query :

  IEnumerable<string> results = from DataRow myRow in tempDT.Rows where myRow.Field<Int32>("kodId") == id && myRow.Field<Int32>("RO") <= Convert.ToInt32(rez) && myRow.Field<Int32>("RD") > Convert.ToInt32(rez) orderby myRow.Field<int>("kodO") select myRow.Field<string>("Text");

  the variables have these values : id =1073754112 and rez="0" 

  and the datarow has these : kodId=1073754112, kodO=1, RO=0, RD=32767 Text ="<test/>"

  but I am getting exception :Specified cast is not valid.

  So maybe my syntax is bad, I don't know, because Linq is something new for me, so I woul be very happy if somebody has any advice 

  Linq DataTable

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  mameenkhn

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  Re: LINQ to Datatable

  Apr 08, 2012 03:38 AM|LINK

  you have to use tempDT.AsEnumerable()

  check it out

  IEnumerable<string> results = from myRow in tempDT.AsEnumerable() where myRow.Field<Int32>("kodId") == id && myRow.Field<Int32>("RO") <= Convert.ToInt32(rez) && myRow.Field<Int32>("RD") > Convert.ToInt32(rez) orderby myRow.Field<int>("kodO") select myRow.Field<string>("Text");

  List<string> results = (from myRow in tempDT.AsEnumerable() where myRow.Field<Int32>("kodId") == id && myRow.Field<Int32>("RO") <= Convert.ToInt32(rez) && myRow.Field<Int32>("RD") > Convert.ToInt32(rez) orderby myRow.Field<int>("kodO") select myRow.Field<string>("Text")).ToList();
  

  
  
  
  

  Linq DataTable

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  Muhammad Amin
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  • Edited by mameenkhn on Apr 08, 2012 03:40 AM
  • Marked as answer by medivo on Apr 08, 2012 10:51 AM
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  medivo

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  Re: LINQ to Datatable

  Apr 08, 2012 10:31 AM|LINK

  Well thank you mameenkhn , it helped me to move a bit, but the problem is not solved yet and I am getting the exception again, but not when executing the command, but aafter, when I am trying to loop trought the results. And I have discovered this part :

  && myRow.Field<Int32>("RO") <= Convert.ToInt32(rez) && myRow.Field<Int32>("RD") > Convert.ToInt32(rez) orderby myRow.Field<int>("kodO")

  as the source of my problem, because when I use only

  IEnumerable<string> results = from myRow in tempDT.AsEnumerable() where myRow.Field<Int32>("kodId") == id select myRow.Field<string>("Text");

  it works perfectly, but I need the conditon to be in the query

  • Edited by medivo on Apr 08, 2012 10:33 AM
  • Edited by medivo on Apr 08, 2012 10:34 AM
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  mameenkhn

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  Re: LINQ to Datatable

  Apr 08, 2012 10:38 AM|LINK

  What exception are you getting?

  how are you looping through?

  Please 'Mark as Answer' if my post helped you
  --------------------------------------------------
  Muhammad Amin
  محمد امين
  • Edited by mameenkhn on Apr 08, 2012 10:39 AM
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  medivo

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  41 Posts

  Re: LINQ to Datatable

  Apr 08, 2012 10:51 AM|LINK

  It was the invalid cast again, but I have solved it few minutes ago and now I feel really stupid, because it was caused by bad sizes of integers. In the DB the fields are smallints so int16 but I used int32 in the query. But thank you to help me improve my linq knowledge

  Have a nice day

  • Marked as answer by medivo on Apr 08, 2012 10:51 AM