When using SQL Developer versions that require Java 7 or higher (4.1.x requires Java 8), download a jtds 1.3.1 driver from ...
1. Extract jtds-1.3.1.jar from the jtds-1.3.1-dist.zip file.
2. Use Tools > Preferences > Database > Third Party JDBC Drivers to add an entry for that jar file.
3. After this, the New / Select Database Connection dialog will display tabs for SQLServer and Sybase.
When I use the above directory for the jar file, the only database that SQL Developer 4.1.1 connects to is Oracle.
Oracle JDBC jar files (e.g. ojdbc6.jar, ojdbc7.jar, etc) are for connecting to Oracle databases.
What is missing?
A JDBC jar file for connecting to Sql Server.
Use your search engine and search for JDBC jar Sql Server and you will find links to 3rd party jars for that DB.
I think this would work. I was reading an old article I wrote when SQL Server 2005 was introduced, there was a similar fix at that time.
those articles won't help you, but our OTN pages will. go to the migrations section and pull up the JDBC driver requirements for SQL Server/Sybase