Adding a transaction row for a specific client ID

I need some help with building an input form please. I have two tables, a client table and a transaction table. The client table has a unique client ID and other details like first name, last name etc. The transaction table has a unique transaction ID+fields relating to details about items purchased.

In my input screen for a new transaction I'd like the user to be able to select a client name (first name+last name) and then fill in the transaction details for that client.

I've been playing with a Picklist and a Column List but have not been able to get it to work yet. Any hints on how to achieve this please?

Thanks

Hi @Josh-7496, welcome to the community! I had a couple quick questions before I elaborate further on some ideas - You mentioned about the ability for the user to select by first name and last name (presumably in a drop down) - a) What happens if there are two matching names? a) Do you have a requirement to have the first name and last name in separate columns?

The matching names seems like it would be an issue and therefore the unique client ID might be more appropriate for a drop-down. But wanted to understand your use case a bit more.

Looking forward to your response!