This section covers three features of Apex that control how transactions are processed by the database:
Data Manipulation Language (DML) database methods—DML database methods are much like DML statements from Chapter 4, but add support for partial success. This allows some records from a batch to succeed while others fail.
Savepoints—Savepoints designate a point in time that your code can return to. Returning to a savepoint rolls back all DML statements executed since the establishment of the savepoint.
Record locking— ...