Always use COMMIT or ROLLBACK explicitly if working in transactional mode. If auto-commit mode is on (default in some databases), each DML statement is automatically committed.

Autocommit controls whether each SQL statement is automatically committed after execution or if manual transaction control is required. - **SET autocommit = 0**: Disables autocommit mode, meaning that ...

Every Transact-SQL statement is committed or rolled back when it completes. If a statement completes successfully, it is committed; if it encounters any error, it is rolled back.