Multiple join

[najihyeon]

Hello,

As far as I know, the joiner node can join only two tables in Knime.
I want to know the different ways to join more than two tables except for SQL related nodes.

Thank you very much!

Best regards,
JH

[kowisoft]

Dear @najihyeon ,

Welcome to the forums

maybe I am mistaken but as far as I know you can only join 2 tables together, assuming we’re talking about “join” (different table structures) compared to “concatenate” (similar table structures).

The only other solution I would see is exactly what you mentioned, using DB nodes and their underlying SQL statements or directly SQL.

This also seems to make sense, as the interface of the Joiner in the first tab basically allows 2 fields to match, not less and not more (so to say).

But of course, you can chain more than one join node together.

Hope this helps. If someone else knows more and thinks I’m wrong, please correct me

Best
Phil

[aworker]

Hi @najihyeon & welcome to the KNIME forum,

A possible solution to do multiple joining is to wrap the -joiner- node using a recursive loop if the rules for joining are always the same:

Recursive Loop Start

Recursive Loop End

Doing this way, it makes the -joiner- node an universal multi joiner.

May be you could tell us a bit more about your data and how you need to join it?

Hope it helps.

Best
Ael

[Daniel_Weikert]

Another alternative is the scripting node (e.g. python)
br