This might be the most important set of preferences in Oracle SQL Developer. The settings on this page directly impact how your queries run and the results they return.
One of the most curious and fun to debug questions I get from users is something along the lines of…
Why does my query return X in SQL Developer but Y in SQL*Plus or _________________ ?
Most of the time, it comes down to differing NLS parameters.
On a Windows machine, the Oracle Client install and associated programs will write to the Windows Registry to maintain the NLS Parameters. SQL Developer is a Java application and doesn’t use the client, or the Windows registry.
Instead, it stores its own set of independent NLS parameters. If your query results differ, this is the first place to look to.
And if you want to have some fun with someone, change their NLS Sort setting.