Using Group by for more than two columns using Linq

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, , ,
1

Hi all,

Can anyone please help me how to use group by function in Linq query for more than two columns.
@ppri1
o1

I require output as above

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@Gattu_Monika

Adding by , syntax within the LINQ Query Syntax

up to three columns we do add it to the group by clause like:

(From d in dtData.AsEnumerable
Group d by k1=d(0)… , k2=d(3)… , d(5)… into grp=Group
[the other part of the implementation]
…
we can also use more, but the readability goes down

in case of more columns we can check for different options

The string Concat trick:

arrColSet = {"C1", "C5", "C7"}
(From d in dtData.AsEnumerable
Let x = String.Join("_",arrColSet.Select(Function (x) d(x).toString))
Group d by k=x into grp=Group
[the other part of the implementation]

The string Concat trick with take/skip:

(From d in dtData.AsEnumerable
Let x = String.Join("_", d.itemArray.Skip(2)Take(5).Select(Function (x) x.toString)
Group d by k=x into grp=Group
[the other part of the implementation]

As a variation of this, we can also set up a helper data column and can shift back to one column for the grouping referring to the helper column

the main focus is to set on the key k=XXX, because k has to be of a datatype that will support comparisation by default

1 Like
3

@ppr Thanks for your reply…I will try like mentioned above

4

@Gattu_Monika
with the updated samples from above give a try on

prepare target datatable with build datatable - dtTarget
Cols: Id, Name, City, Count, Sum

Assign activity:
LHS: dtTarget
RHS:

(From d in dtData.asEnumerable
Group d by k1=d(0).toString, k2=d(1).toString, k3=d(2).toString
let sm = grp.Sum(Function (x) CInt(x("Value").toString.Trim))
let ra = new Object({k1,k2,k3, grp.Count, sm}
Select r = dtTarget.Rows.add(ra)).CopyToDataTable

feel free to shift to col names instead of index and to trim the keys

3 Likes
5

@ppr Thanks It worked well…as I need to group only three columns I used first method…Thanks for your help

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