How to aggregate in a LINQ query

[=?Utf-8?B?UGFvbG8=?=]

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.Transaction
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

[Peter Duniho]

On Thu, 13 Nov 2008 21:14:58 -0800, Paolo
<Pa***@discussions.microsoft.comwrote:

[...]
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

[=?Utf-8?B?UGFvbG8=?=]

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
<Pa***@discussions.microsoft.comwrote:

[...]
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

[Peter Duniho]

On Thu, 13 Nov 2008 21:54:23 -0800, Paolo
<Pa***@discussions.microsoft.comwrote:

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

[=?Utf-8?B?UGFvbG8=?=]

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
<Pa***@discussions.microsoft.comwrote:

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