Setting Savepoints in Transactions

The SAVEPOINT statement marks a savepoint in a transaction-a point to which you can later roll back. Savepoints are optional, and a transaction can have multiple savepoints. Example 3-9 does a transaction that includes several DML statements and several savepoints, and then rolls back the transaction to one savepoint, undoing only the changes made after that savepoint.

Example 3-9 Rolling Back a Transaction to a Savepoint

Check REGIONS table before transaction:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
         1 Europe
         2 Americas
         3 Asia
         4 Middle East and Africa
         5 Africa

5 rows selected.

Check countries in region 4 before transaction:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 4
ORDER BY COUNTRY_NAME;

Result:

COUNTRY_NAME                             CO  REGION_ID
---------------------------------------- -- ----------
Egypt                                    EG          4
Israel                                   IL          4
Kuwait                                   KW          4
Nigeria                                  NG          4
Zambia                                   ZM          4
Zimbabwe                                 ZW          4

6 rows selected.

Check countries in region 5 before transaction:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 5
ORDER BY COUNTRY_NAME;

Result:

no rows selected

Transaction, with several savepoints:

UPDATE REGIONS
SET REGION_NAME = 'Middle East'
WHERE REGION_NAME = 'Middle East and Africa';

UPDATE COUNTRIES
  SET REGION_ID = 5
  WHERE COUNTRY_ID = 'ZM';
SAVEPOINT zambia;

UPDATE COUNTRIES
  SET REGION_ID = 5
  WHERE COUNTRY_ID = 'NG';
SAVEPOINT nigeria;

UPDATE COUNTRIES
  SET REGION_ID = 5
  WHERE COUNTRY_ID = 'ZW';
SAVEPOINT zimbabwe;

UPDATE COUNTRIES
  SET REGION_ID = 5
  WHERE COUNTRY_ID = 'EG';
SAVEPOINT egypt;

Check REGIONS table after transaction:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
         1 Europe
         2 Americas
         3 Asia
         4 Middle East
         5 Africa

5 rows selected.

Check countries in region 4 after transaction:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 4
ORDER BY COUNTRY_NAME;

Result:

COUNTRY_NAME                             CO  REGION_ID
---------------------------------------- -- ----------
Israel                                   IL          4
Kuwait                                   KW          4

2 rows selected.

Check countries in region 5 after transaction:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 5
ORDER BY COUNTRY_NAME;

Result:

COUNTRY_NAME                             CO  REGION_ID
---------------------------------------- -- ----------
Egypt                                    EG          5
Nigeria                                  NG          5
Zambia                                   ZM          5
Zimbabwe                                 ZW          5

4 rows selected.

ROLLBACK TO SAVEPOINT nigeria;

Check REGIONS table after rollback:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
         1 Europe
         2 Americas
         3 Asia
         4 Middle East
         5 Africa

5 rows selected.

Check countries in region 4 after rollback:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 4
ORDER BY COUNTRY_NAME;

Result:

COUNTRY_NAME                             CO  REGION_ID
---------------------------------------- -- ----------
Egypt                                    EG          4
Israel                                   IL          4
Kuwait                                   KW          4
Zimbabwe                                 ZW          4

4 rows selected.

Check countries in region 5 after rollback:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 5
ORDER BY COUNTRY_NAME;

Result:

COUNTRY_NAME                             CO  REGION_ID
---------------------------------------- -- ----------
Nigeria                                  NG          5
Zambia                                   ZM          5

2 rows selected.

See Also: Oracle Database SQL Language Reference for information about the SAVEPOINT statement