There are several SQL statements you cannot use ROLLBACK as MySQL Implicitly Commits those Statements such as:
CREATE / ALTER / DROP DATABASE
CREATE /ALTER / DROP / RENAME / TRUNCATE TABLE
CREATE / DROP INDEX
CREATE / DROP EVENT
CREATE / DROP FUNCTION
CREATE / DROP PROCEDURE
For Such Statements it doesn't matter weather you are using explicit Commit or not the statement will Commit implicitly ass soon as you execute it.