Disable autocommit for SQL Server connection in Oracle SQL Developer
SQL Server uses autocommit mode by default. This cannot be changed permanently.

There are two ways implicit transactions (non-autocommit) can be turned on:


At the server level such that new sessions use it by default, using sp_configure 'user options' -- this may or may not work depending on how SQL Developer was implemented.
For a session, using SET IMPLICIT_TRANSACTIONS ON.