DML - (Data Manipulation Language )

These commands used to manage data within schema objects.

1) SELECT

This command is used to retrieve data from the database

Example

SELECT * FROM EMP;

2) INSERT

This command is used to insert data into a table.

Example

To insert into a table with specifying the column name

INSERT INTO T1 (A) VALUES(6);

To insert into a table without specifying the column name

INSERT INTO T1 VALUES(5);

3) UPDATE

This command is used to update data in a table.

Example

To update the entire row in a table

UPDATE T1 SET A=8;

To update a particular row in a table

UPDATE T1 SET A=7 WHERE A=6;

4) DELETE

This command is used to remove one or more rows from a table. It can be rollback.

Example

To delete all rows from a table

DELETE FROM T1;

To delete one row from a table

DELETE FROM T1 WHERE A=4;

5) MERGE

Merge is an update plus insert. It will be updated when it is matched and will be inserted when it is unmatched.

Example

MERGE
INTO T2
USING T1
ON (T1.A = T2.A)
WHEN MATCHED
THEN UPDATE
SET T2.B = T1.B
WHEN NOT MATCHED
THEN
INSERT (T2.A,T2.B) VALUES(T1.A,T1.B);