7-2
Objectives
•
Insert new rows into a table.
•
Update existing rows in a table.
•
Delete rows from a table.
•
Explain transaction controls and their importance.

7-3
Data Manipulation and
Transaction Control Commands
Command
INSERT
UPDATE
DELETE
COMMIT
SAVEPOINT
ROLLBACK
Description
Adds a new row to the table.
Modifies existing rows in the table.
Removes existing rows from the table.
Makes all pending changes permanent.
Allows a rollback to that savepoint marker.
Discards all pending data changes.

7-4
Inserting New Rows into a Table:
Syntax
•
Add new rows to a table by using the INSERT command.
INSERT INTO
VALUES
table [(column [, column...])]
(value [, value...]);
•
Only one row is inserted at a time with this syntax.

7-5
Inserting New Rows: Example
•
Insert a new row containing values for each column.
•
Optionally list the columns in the INSERT clause.
INSERT
VALUES
1 row created.
INTO s_dept
(11, 'Finance', 2);
•
List values in the default order of the columns in the table.
•
Enclose character and date values within single quotation marks.

7-6
Inserting New Rows with Null Values
Implicit Method
•
Omit the column from the column list.
INSERT INTO
VALUES
1 row created.
s_dept (id, name)
(12, 'MIS');
Explicit Method
•
Specify the NULL keyword or the empty string ('') in the VALUES list.
INSERT INTO
VALUES
1 row created.
s_dept
(13, 'Administration', NULL);

7-7
Copying Rows from Another Table
•
Write your INSERT command with a subquery.
INSERT INTO history(id, last_name, salary, title, start_date)
SELECT id, last_name, salary, title,start_date
FROM s_emp
WHERE start_date < '01-JAN-94';
10 rows created.
•
Do not use the VALUES clause.
•
Match the number of columns in the INSERT clause to those in the subquery.

7-8
Updating Rows in a Table: Syntax
•
Modify existing rows with the UPDATE command.
UPDATE table
SET column = value [, column = value]
[WHERE condition];

7-9
Updating Rows: Examples
•
Transfer employee number 2 to department 10.
UPDATE
SET
WHERE s_emp dept_id = 10 id = 2;
1 row updated.
•
Transfer employee number 1 to department 32 and change the salary to 2550.
UPDATE
SET s_emp dept_id = 32, salary = 2550
WHERE id = 1;
1 row updated.

7-10
Updating All Rows in the Table
All rows in the table will be updated if you do not add the WHERE clause.
UPDATE s_emp
SET commission_pct = 10;
25 rows updated.

7-11
Deleting Rows from a Table: Syntax
•
Remove existing rows by using the DELETE command.
DELETE [FROM]
[WHERE table
condition];
•
Remove all information about employees who started after January 1, 1996.
DELETE FROM s_emp
WHERE start_date > '01.01.1996';
1 row deleted.

7-12
Deleting Rows: Example
•
Delete all the rows in the table by excluding the
WHERE clause.
DELETE FROM test;
25,000 rows deleted.
•
Confirm the deletions.
SELECT * FROM no rows selected test;

7-13
Database Transactions
•
Contain one of the following statements:
–
DML commands that make up one consistent change to the data
–
One DDL command
–
One DCL command
•
Begin when the first executable SQL command is executed.
•
End with one of the following events:
–
COMMIT or ROLLBACK
–
DDL or DCL command executes (automatic commit)
–
Errors, exit, or system crash

7-14
Advantages of COMMIT and ROLLBACK
•
Ensure data consistency.
•
Preview data changes before making changes permanent.
•
Group logically related operations.

7-15
Controlling Transactions
COMMIT
INSERT
UPDATE
Savepoint
Marker A
Savepoint
Marker B
INSERT
DELETE
ROLLBACK
ROLLBACK ROLLBACK to A ROLLBACK to B