How to show drop down from ref column and save user choice at the same time?

[YotsubaT]

Hi community,

Just updated my post to make it simpler. I'm working with 3  2 datasets:

• a. to read from
• b. to write to
• c. has one column "name" for user to choose from.

I need to do below things in action of clicking a button from detailed list of table a (if possible):

1. show a dropdown of Enum column "name" from table c  b
2. record user choice in table b - column "assigned_name"
3. pass value from column "product" from table a to b

I have completed setting up a button and number 3 successfully. Could someone please help me with 1 and 2? Potentially need to set up ref column in table a?