Adding a joint table in existing app--How do I connect the data?

[yumei]

I have an app that is running and there's plenty of data in the various tables. Now I have added a new table, a joint table called "MentorStudents". It has two foreign key columns "Ref" to "Mentor" table and "Student" table.  I thought that once I have established the relationships, existing data would show up. Of course it didn't (the table is still empty).

How do I get this new table populated with existing data? I googled and found a reference to "restart" the app. But I don't know how to restart it aside from refreshing the columns.

[dbaum · Accepted solution]

I don't think your new table is going to populate automatically. If you have the relationships between Mentors and Students already represented in either or both of those tables, you could likely devise an app action (or just a formula directly in a spreadsheet data source) to perform the initial population of the new table's rows. If those relationships are not already represented in your app's data, you'll need to create the rows manually--again, potentially directly in the data source and not necessarily via the app interface.

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@yumei wrote:

a reference to "restart" the app

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I don't know what this might be. If you think it will help, try signing out and signing back in to AppSheet

[yumei]

Thanks! I sorta suspected as much, but I thought that if virtual columns could assemble data on the fly, why not an actual table (I played around with query formulas without any success). 

[yumei]

Followup question - just so I understand better how AppSheet works: Joint tables in AppSheet don't assemble information on the fly, do they? I mean: you cannot set up a joint table and expect it to fetch relevant data to display - is that right?

Reason I'm dwelling on this: I managed to use various expressions to retrieve and display data that I need, but I feel things are getting too convoluted. I wish I had set up joint tables from the beginning. So I am kinda thinking I might retroactively put in a clean remedy.

[dbaum]

There's no scenario where AppSheet automatically generates rows in any table.

For columns with an App formula expression:

• If the column exists in the table's data source, it is only updated for a given row when the row itself is explicitly updated.
• If the column does not exist in the table's data source (i.e., it's a virtual column), it's up-to-date value is always available for reference for all rows in the table.