This procedure rolls back an ongoing transaction. It will fail if there is no active transaction, if autocommit mode is active, or if no connection to the database has yet been made. There is no explicit "begin transaction" command; a transaction starts when a command is issued to the SQL server and autocommit is not set.
Some databases, including MySQL automatically issue an implicit commit when a Database Definition Language (DDL) statement such as "DROP TABLE" or "CREATE TABLE" is issued within a transaction. The implicit commit will prevent the rollback of the other changes within the transaction boundary.
[DB] is "MySQL.MySQL_Driver", "PostgreSQL.PostgreSQL_Driver", or "SQLite.SQLite_Driver"