It is used by manipulate the data that is stored in the DB
DML operations can be rolled back
Oracle INSERT, UPDATE, DELETE, MERGE, Multi INSERT Statements
INSERT Command
INSERT INTO emp VALUES (101, 'Sami', 'G. Manager', 8 Aug 1998, 2000);
INSERT INTO emp (empno, ename, sal) VALUES (102, 'Ashi', 5000);UPDATE Command
UPDATE emp SET name='Mohd Sami', sal=sal+(sal*10/100) WHERE empno=102;
UPDATE emp SET sal=sal+(sal*5/100);DELETE Command
DELETE FROM emp WHERE empno=102;
DELETE FROM emp;MERGE Command
Merge Command is used to synchronize two tables based on the difference in them, if the same row exist in both then UPDATE the value in target table else INSERT value into target table
The decision whether to update or insert into the target table is based on a condition in the ON clause.
MERGE INTO sales_history sh
USING sales s
ON (s.prod=sh.prod AND s.month=sh.month)
WHEN MATCHED THEN UPDATE SET sh.amount=s.amount
WHEN NOT MATCHED THEN INSERT VALUES (prod, month, amount);