Data
is manipulated, or modified, by the DML class of SQL statements: INSERT, UPDATE, DELETE, and
MERGE.
These statements execute as part of a transaction, which starts with the first
successful DML statement and ends with either a COMMIT or ROLLBACK
command.
A transaction is either entirely committed or entirely rolled back.
A transaction is either entirely committed or entirely rolled back.
In
addition to the explicit COMMIT or ROLLBACK
commands, they can also occur implicitly. For example, rollback may occur if
there is a process or system failure. Commit may occur after a DDL command,
such as the CREATE
TABLE
command.
Note: The MERGE command performs a combination of
DML commands to merge data from one table into another.
