db looping

I have searched but am confused by “db looping” node. I have studied the examples but not sure I understand it compared to what I need. I will try to simplify what I am hoping to accomplish.

Let’s assume I have a table of transactions which has a few million rows. Included in transaction columns is a customer_id.

My workflow is that I pull from a spreadsheet to get a set of customers (say 10 that includes a customerid) then I want to pull from transactions where Transaction.customerid = spreadsheet.customer_id.

Option 1: I could pull customers from spreadsheet and join to transactions but pulling the transactions into knime takes time and hoping I can more or less use db looping to pull just the transactions I need.

Option 2: Another approach I guess is to import the customer_id into the database and then join in database.

I suspect option 2 likely is faster, but I’d like to try option 1 first. The problem is the db looping node does not seem very clear to me.

In the db looping configuration I see three areas:

Database Column List

Column list

SQL query

SELECT * FROM #table# AS “table”

Here’s where it’s a bit fuzzy.

is #table# is my example the transactions table (how to I ensure it is?) Then do I add to query where transaction.customerid in ($customerid$) <from spreadsheet?>

I have connected spreadsheet customer_id table to input port 0 and the query of transactions to port 1. If I run it run it, in the end I have to cancel it as it never finishes.

Question 1: Have i missed how to write query in sql query portion?

Question 2: Maybe this is not right approach and I need to use option 2 or another method.

Thoughts?

Thanks,

Jeff