Thanks for posting! Here's one way you can do this:
We'll assume the following for the example:
In Manage > Database > Relationships tab, set the relationship so that Username = Username. Enter Browse Mode for the User Layout and add values in the Username and UserID fields. Once you have some records in the User Layout, go to the Issues Layout and enter Layout Mode.
In the Issues Table Layout Mode, double click on the Username field to bring up the Field Control/Setup window. Change the 'display as' drop down menu from Edit Box to Pop up Menu. Next, click on the 'display values from' drop down menu and select 'Manage Value Lists.' Click on 'New.'
Give the Value List a name and check the 'Use values from field' option. Click on the 'Specify field...' button. Click on the 'Use values from first field' drop down menu, choose the Users Table and select the Username field from the list. Make sure that 'Include all values' is selected and then click 'OK' out of each window. We've just set it up so that our pop up menu will display all of the Username values that you added in the User Table
We're now back to the Issues Table Layout Mode. Double click on the User ID field to bring up the Field Control/Setup window. On the right hand side, click on the 'Display data from' drop down menu and choose the User Table. A list of the fields from the User Table will now appear. Highlight '::User ID' and click OK. Enter Browse Mode.
Now, when you click on the Username field, you will see a list of values pulled from the User Table. When you choose a value from the list, the appropriate User ID will populate.
Hopefully this helps or points you in the right direction. Let me know if you need further clarification.
Thanks for that solution. It's close to what I'm trying to achieve, but not quite there. I should have provided more details originally I guess.
I want to store user names by first and last names (for personalized emails). I created a calculation field that joins them into a full name to show on the Issues layout.
I had done the same sort of thing that you suggested, using a popup menu populated with those full names. I had made the relation between the two tables on the userID field. That results in a layout in which I cannot access the Username field. Any suggestions on fixing that?