Understanding DML statements

Data Manipulation Language (DML) statements are used to manipulate data in existing tables. INSERT, UPDATE, and DELETE are examples of DML statements. We use INSERT to add a new record to the table, UPDATE to modify one or more columns of a table, and DELETE to remove a record from the table.

The following is an example of an INSERT statement. We insert a new record in the regions table of the HR schema:

SQL> INSERT INTO regions VALUES (5, 'Australia');
1 row created.
SQL> COMMIT;
Commit complete.
SQL>

An example of the UPDATE statement is shown next, where we modify the value of region_name from Australia to Aus and NZ. This is done as follows:

SQL> UPDATE regions SET region_name = 'Aus and NZ' Where region_id = 5;
1 row updated.
SQL> COMMIT;
Commit complete.
SQL>

The following is an example of the DELETE statement. We remove the newly added record from the regions table as follows:

SQL> DELETE FROM regions Where region_id = 5;
1 row deleted...