Getting unique values out of two data tables


I have two data tables with the same structure (the number of columns is the same and the name of columns are the same)

My first data table is named datatable1 and my second data table is named: datatable2

What I need is:

I need to compare these two data tables using three columns, and if the rows in these columns are the same then I need to delete them so the expected outcome is to have unique rows in new datatable 3 by comparing only 3 columns.

Could you please help me with this I’m very stuck and I need detailed instruction.


Can you provide the name of the 3 columns?

In the meantime, take a look at this reply from the great @ppr

You could also try a “Join datatable” activity and then remove “remove duplicate” rows activity.



Hi @JennZabba

Try this

uniqueRows = (From row1 In datatable1.AsEnumerable()
Where Not datatable2.AsEnumerable().Any(Function(row2) row1(“Column1”).Equals(row2(“Column1”)) And
row1(“Column2”).Equals(row2(“Column2”)) And
Select row1).CopyToDataTable()

Hope this helps!!

but I need this to be in a data table, my expected outcome needs to be a data table

Hello, this is what I need:

Column names lets call them col 1 col 2 and col 3, can you help please?

We can work with Join Data Table Activity and postproces the Join Result

Or Using some Linqs - Match Approach

Assign Activity - Just adapt to your Column names
arrColSet = {“Column1”,“Column2”,“Column3”}

Assign Activity:
Dt1OnlyRows | List(Of DataRows) =

(From d In datatable1 .AsEnumerable()
Let lcs = arrColSet.Select(Function (x) d(x).ToString.Trim)
Let chk = datatable2.AsEnumerable().Any(Function (d2) arrColSet.Select(Function (x2) d2(x2).ToString.Trim).SequenceEqual(lcs))
Where Not chk
Select r = d).ToList

Assign Activity:
Dt2OnlyRows | List(Of DataRows) =

(From d In datatable2 .AsEnumerable()
Let lcs = arrColSet.Select(Function (x) d(x).ToString.Trim)
Let chk = datatable1.AsEnumerable().Any(Function (d2) arrColSet.Select(Function (x2) d2(x2).ToString.Trim).SequenceEqual(lcs))
Where Not chk
Select r = d).ToList

Finaly when there are rows returned
Assign Activity
dtUniqueRows | DataType: DataTable =
Dt1OnlyRows.Concat(Dt2OnlyRows ).CopyToDataTable

A more unusual approach, but also working one could be the Group By Approach

Assign Activity
dtMerge = datatable1 .Copy()

Merge DataTable Activity| Merge datatable2 to dtMerge

Assign Activity
dtUniqueRows | DataType: DataTable =

(From d in dtMerge.AsEnumerable()
Group d by k1=d("Column1").ToString.Trim,k2=d("Column2").ToString.Trim,k3=d("Column3").ToString.Trim into grp=Group
Where grp.Count = 1
Select r = grp.First()).CopyToDataTable

Handling empty result we can do:

here it shows the common rows (as yellow is present in both)

But initial was told:

Maybe you clear the requirements

BTW: for the Match Approach LINQ we would only modify the check / filter condition

Also have a look here:


You can use this

first merge the datatables together

using merge datatable actvity into one datatable say mergeddt

then use mergeddt = mergeddt.AsEnumerable.GroupBy(function(x) x("FirstColumn").ToString+x("SecondColumn").ToString + x("ThirdColumn").ToString).Where(function(x) x.Count=1).SelectMany(function(x) x).CopyToDataTable


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