Subtract from a List

I’m new to CODA, but I used Airtable for 2 years.
I managed to do a lot, but got stuck with custom function.

At the “Preceding Task” column I refer to the “Task ID #” column.
Here I want to be able to select only tasks, that have the same “Project” but not itself:

Thanks in advance!

Hi @Attila_Nagy

Welcome to community.
assuming that 2 tasks may have the same Task ID #, we’ll need a unique key, row id for example
Then you filter the table with same project as current row, but different rowid

If you are absolutely sure that 2 asks cannot have the same Task ID #, you can use this as a key instead of row id.

Is that clear for you ?



Hi Quentin,
thank you for your help!
I immediately tried it, but I get instead of the “T” the row symbols.
Besides that how do I get “Row ID 123”, because I just get “RowId()”?



Yes sorry, this is because in my quick example I used select list for project while you used a relation. If I create a table I’ve got a link to project table

And to automatically generate rowid column, just type “row” when you add a new column, and rename it as you wish


OK, I think I understand.
You made a column, that represents the column ID.
Do I have to do that too or can I just use the “RowId()” in the formula?

Just use rowid, or any column that you are sure will be a unique reference to a given row

There are no errors now in the formula, but it allows me to select itself and also tasks from other projects:

WOW ! Truly sorry, I read too quickly, didnt see you wanted to use it in filtering options to select it manually. Truly sorry, I’m too tired…

So you column “Preceding Task” is a relation ot your “projet tasks” itself
and then set this filter

That should be alright now


No problem, it works perfect now!
Thanks a lot! :wink:
Have a good rest!

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