I was attempting to add a PK to a View to see if it would make some Visual Studio developers lives easier and the SQL that Toad generates for this is incorrect and will not run. Here is a screen shot of the Create Constraint Window:
You can see this is a View (circled in Orange in the above image). When you click "Show SQL" you see the following:
It should read ALTER VIEW... not ALTER TABLE...
I am connecting to an Oracle 19 DB with Oracle Client 22.214.171.124 . Let me know if you need any additional info.