Getting error "SQL0204N...undefined name" when running query in Editor window. (4319258)

When running a query inside the Editor window without qualifying the library name in the query gave the error:

"SQL0204N...undefined name"

The same query runs find in the Query Builder, why is that?

For example, in the Editor window, the below query will not work.

   SELECT * FROM emp;

The qualifier "dan" Needs to be added to get

   SELECT * FROM dan.emp;

In the Query Builder, "SELECT * FROM emp" will run

Go to Toad Option | Database | Query Builder and check the option to "Use Fully Qualified object names". This option let you run the query without qualifying it.