Combining Tables: Combine a possibly empty table with a filled

Hi Everyone!

I am currently struggling with a combination of two tables.
The two tables have the exact same headers. Usually both tables contain data, so that I want to combine them in one combined Table.
However, it can happen, that one table is without data. Then all possible ways fail

Does anyone have an idea how to solve this?

Hello @tassmann
As far as I remember ‘Concatenate’ node can bind rows from empty tables, this will happens just if headers are exact the same in terms of column names and data type/format .


Hi @gonhaddock
Thanks for the answer, However, I am still haveing an issue
When I use Concatenate and one of the Imput tables is Empty, the Concatenate knot works (see the upper Concatenate in the Picture)
So it works, if my Excel file contains the sheet and the sheet is empty.
But when the sheet is missing, the branch stays red and then the concatenate does not work either…

Any ideas / approaches?

So here, in the picture, the first loop has the sheet, and it contains data.
The second loop has a sheet but there is no data in it
and the thrid loop did not find the sheet (What can happen)

Final version with data:


The Rule Based Rule Filter:
Include TRUE matches


Hello @tassmann
Revisiting your picture, you have an error in your Loop End node, then some error handling has to be implemented before this issue.

If I assume that you are reading from excel files; You can read the tabs of the file in advance and detect if the tab is missed. In this case you can use IF nodes to deliver an alternative solution to the loop, this can be an empty table as in this example (Table Creator) or to read from a dummy file with headers and no data.



@gonhaddock thanks for your input!
I just had a little time today to implement your solution and with a few extra steps I got it to work :slight_smile:
Thanks alot!

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