How to edit data to 2 tables using MySQL Workbench
If you are editing data through the editor(mysqlworkbench) it needs a table on where it should execute the update command and the where column. That's why you can edit the record only when you have executed SELECT * FROM table because result of this query has primary key and table So Updating the data through workbench will be allowed

If you are using join to get the record then the editor displays the record of both the tables. And workbench(editor) won't get the table and primary key to update.