Concatenate multiple tables together in KNIME

I have several tables (say 5) with data at different evaluation dates. The column names in each table are all the same.

I would like to simply “union” these 5 tables together, so that all data is in one table. What would be the best way to do this in KNIME? From what I can tell, this can only easily be done with 2 tables…

I am basically looking for the KNIME equivalent to using multiple "UNION ALL"s in SQL.

Hi,

You can use the “Concatenate (Optional-in)” Node if you want to concatenate more than one input.

Best,

Christian

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Thank you. However, it looks like the max I can do is 4 tables? Is there no way to do any number of tables?

Hi again,

You would have to use several instances of the node for this.

Cheers,

Christian

darn, that’s what I figured. thank you

Hello, I’m just starting in Knime. I need to use this “Concatenate (Optional-in)”. Can you please tell me how to get it? I can’t find it in the Node repository.

Thank you,

Mona

Hi @MJRIOUX and welcome to the forum.

This topic is a little bit old. Since it was originally posted, we have changed the name of the node to just Concatenate. The new version of the node in KNIME 4.1 allows you to stack as many tables as you need to using dynamic ports - see here: https://www.knime.com/whats-new-in-knime-41#technical-improvements

5 Likes

You could use several concatenation nodes and create a meta node with multiple inputs.

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