How to aggregate in a LINQ query

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  • =?Utf-8?B?UGFvbG8=?=
    #1

    How to aggregate in a LINQ query

    I have a LINQ query which returns a sequence of rows all of which contains a
    decimal field (T_Amount) e.g.

    var trans =
    from trans in dataSet.Transac tion
    where .... (filters)
    ....
    select new
    {
    trans.T_Date,
    p.P_Name,
    c.C_Description ,
    s.S_Description ,
    pm.Value,
    trans.T_Amount <<<< want to sum on this
    };

    I want to sum the values in T_Amount and show it in a label on a windows form.

    I'd appreciate an example of how to construct such an aggregation, returning
    the
    total for sequence. I've done a fair amount of research but haven't found a
    workable example.

    Thanks
    Tags: None
    • Peter Duniho
      #2
      Re: How to aggregate in a LINQ query

      On Thu, 13 Nov 2008 21:14:58 -0800, Paolo
      <Paolo@discussi ons.microsoft.c omwrote:
      [...]
      I want to sum the values in T_Amount and show it in a label on a windows
      form.
      >
      I'd appreciate an example of how to construct such an aggregation,
      returning the
      total for sequence. I've done a fair amount of research but haven't
      found a
      workable example.
      Did you look at the Enumerable.Sum< TSource>() method? Something like this:

      decimal sum = trans.Sum(t =t.T_Amount);

      Might do what you want.

      Pete

        Comment

        • =?Utf-8?B?UGFvbG8=?=
          #3
          Re: How to aggregate in a LINQ query

          Pete: Thanks - yes, I've been poring over the Enumerable class and decided
          Sum() was what I needed. I just didn't know how to express the code.

          Now, where do I put decimal sum = trans.Sum(t =t.T_Amount); ?

          If I put it after the select new {...}; statement I get "The name 'trans'
          does not exist in the current context".

          "Peter Duniho" wrote:
          On Thu, 13 Nov 2008 21:14:58 -0800, Paolo
          <Paolo@discussi ons.microsoft.c omwrote:
          >
          [...]
          I want to sum the values in T_Amount and show it in a label on a windows
          form.

          I'd appreciate an example of how to construct such an aggregation,
          returning the
          total for sequence. I've done a fair amount of research but haven't
          found a
          workable example.
          >
          Did you look at the Enumerable.Sum< TSource>() method? Something like this:
          >
          decimal sum = trans.Sum(t =t.T_Amount);
          >
          Might do what you want.
          >
          Pete
          >

            Comment

            • Peter Duniho
              #4
              Re: How to aggregate in a LINQ query

              On Thu, 13 Nov 2008 21:54:23 -0800, Paolo
              <Paolo@discussi ons.microsoft.c omwrote:
              Pete: Thanks - yes, I've been poring over the Enumerable class and
              decided
              Sum() was what I needed. I just didn't know how to express the code.
              >
              Now, where do I put decimal sum = trans.Sum(t =t.T_Amount); ?
              >
              If I put it after the select new {...}; statement I get "The name 'trans'
              does not exist in the current context".
              After the semi-colon? If so, then you didn't post the actual code you're
              using. The variable "trans" should just be whatever you've assigned the
              query result to. Assuming you've actually named it something other than
              what you showed in your first post (which seems reasonable...I wouldn't
              actually use the same name inside the query as I use for the results),
              then you need to replace the "trans" in the statement I posted with
              whatever the actual variable name is.

              Pete

                Comment

                • =?Utf-8?B?UGFvbG8=?=
                  #5
                  Re: How to aggregate in a LINQ query

                  Pete: thanks again. My original query variable was qryTrans. I must have
                  missed off the 'qry' bit when I cut and pasted the code. Anyway I've made
                  the change and it works perfectly.

                  "Peter Duniho" wrote:
                  On Thu, 13 Nov 2008 21:54:23 -0800, Paolo
                  <Paolo@discussi ons.microsoft.c omwrote:
                  >
                  Pete: Thanks - yes, I've been poring over the Enumerable class and
                  decided
                  Sum() was what I needed. I just didn't know how to express the code.

                  Now, where do I put decimal sum = trans.Sum(t =t.T_Amount); ?

                  If I put it after the select new {...}; statement I get "The name 'trans'
                  does not exist in the current context".
                  >
                  After the semi-colon? If so, then you didn't post the actual code you're
                  using. The variable "trans" should just be whatever you've assigned the
                  query result to. Assuming you've actually named it something other than
                  what you showed in your first post (which seems reasonable...I wouldn't
                  actually use the same name inside the query as I use for the results),
                  then you need to replace the "trans" in the statement I posted with
                  whatever the actual variable name is.
                  >
                  Pete
                  >

                    Comment

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