You will run into an error if you try and use
start transaction;
-- Your SQL statements
commit;
...out of the box on a MySQL database in SQLDeveloper (as Michael mentioned in a comment to another answer.)
In order to get around this error that Michael referenced in his comment you can use the following hint:
/*sqldev:stmt*/start transaction;
-- Your SQL statements
/*sqldev:stmt*/commit;
Found this information here.