It is easy, but takes 3 steps:
- In SQL Developer, enter your query in the "Worksheet" and highlight it, and press F9 to run it. The first 50 rows will be fetched into the "Query Result" window.
- Click on any cell in the "Query Result" window to set the focus to that window.
- Hold the Ctrl key and tap the "A" key.
All rows will be fetched into the "Query Result" window!