Five tables make up my database. I first included those tables, but then removed them because of a relationship compilation problem.
Currently, I'm opening the edmx file and selecting "update model from database" when I want to add them back. Only under the "refresh" tab do I see those tables; not under the add tab.
How can I re-add them?
You will first need to remove the table from your model before you can add it again. In the [model.Store] tree, you can see a list of tables (see 'Type of browser' window; you may access it from the right-mouse click menu). The table will show up in the 'Add' tab in the 'Update Wizard's' first step when you execute 'Update model from database...'
Actions to take:
To remove every mention of a table in your Model:
After reading this and other search options, I have finally discovered a different solution that would enable me to resolve my problem.
From the error message looks like one of your table/view doesn't have a primary key. EF needs every table to have a primary key in order to generate Entity keys. You may still be able to run your application, but I strongly suggest you add primary keys as warned.
If everything is done correctly and the changes are still not visible, try adding a new column or changing the data type.
The best course of action in this situation is to attempt an update manually. If that fails, as advised by @mathijsuitmegen, remove the table and add it again.