ROLLBACK v17

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The ROLLBACK command undoes all database updates made during the current transaction and ends the current transaction.

ROLLBACK [ WORK ];

You can use the ROLLBACK command in anonymous blocks, stored procedures, or functions. In an SPL program, it can appear in the executable section and the exception section.

In this example, the exception section contains a ROLLBACK command. Even though the first two INSERT commands execute successfully, the third causes an exception that results in the rollback of all the INSERT commands in the anonymous block.

\set AUTOCOMMIT off
SET edb_stmt_level_tx TO on;

BEGIN
    INSERT INTO dept VALUES (50, 'FINANCE', 'DALLAS');
    INSERT INTO dept VALUES (60, 'MARKETING', 'CHICAGO');
    INSERT INTO dept VALUES (70, 'HUMAN RESOURCES', 'CHICAGO');
EXCEPTION
    WHEN OTHERS THEN
        ROLLBACK;
        DBMS_OUTPUT.PUT_LINE('SQLERRM: ' || SQLERRM);
        DBMS_OUTPUT.PUT_LINE('SQLCODE: ' || SQLCODE);
END;

SQLERRM: value too long for type character varying(14)
SQLCODE: 22001

SELECT * FROM dept;
Output
deptno  |   dname    |   loc
--------+------------+----------
     10 | ACCOUNTING | NEW YORK
     20 | RESEARCH   | DALLAS
     30 | SALES      | CHICAGO
     40 | OPERATIONS | BOSTON
(4 rows)

This example uses both COMMIT and ROLLBACK. First, the following stored procedure is created. It inserts a new employee.

\set AUTOCOMMIT off
SET edb_stmt_level_tx TO on;

CREATE OR REPLACE PROCEDURE emp_insert (
    p_empno         IN emp.empno%TYPE,
    p_ename         IN emp.ename%TYPE,
    p_job           IN emp.job%TYPE,
    p_mgr           IN emp.mgr%TYPE,
    p_hiredate      IN emp.hiredate%TYPE,
    p_sal           IN emp.sal%TYPE,
    p_comm          IN emp.comm%TYPE,
    p_deptno        IN emp.deptno%TYPE
)
IS
BEGIN
    INSERT INTO emp VALUES (
        p_empno,
        p_ename,
        p_job,
        p_mgr,
        p_hiredate,
        p_sal,
        p_comm,
        p_deptno);

    DBMS_OUTPUT.PUT_LINE('Added employee...');
    DBMS_OUTPUT.PUT_LINE('Employee # : ' || p_empno);
    DBMS_OUTPUT.PUT_LINE('Name       : ' || p_ename);
    DBMS_OUTPUT.PUT_LINE('Job        : ' || p_job);
    DBMS_OUTPUT.PUT_LINE('Manager    : ' || p_mgr);
    DBMS_OUTPUT.PUT_LINE('Hire Date  : ' || p_hiredate);
    DBMS_OUTPUT.PUT_LINE('Salary     : ' || p_sal);
    DBMS_OUTPUT.PUT_LINE('Commission : ' || p_comm);
    DBMS_OUTPUT.PUT_LINE('Dept #     : ' || p_deptno);
    DBMS_OUTPUT.PUT_LINE('----------------------');
END;

This procedure has no exception section. Any errors are propagated up to the calling program.

Then the following anonymous block runs. The COMMIT command is used after all calls to the emp_insert procedure and the ROLLBACK command in the exception section.

BEGIN
    emp_insert(9601,'FARRELL','ANALYST',7902,'03-MAR-08',5000,NULL,40);
    emp_insert(9602,'TYLER','ANALYST',7900,'25-JAN-08',4800,NULL,40);
    COMMIT;
EXCEPTION
    WHEN OTHERS THEN
        DBMS_OUTPUT.PUT_LINE('SQLERRM: ' || SQLERRM);
        DBMS_OUTPUT.PUT_LINE('An error occurred - roll back inserts');
        ROLLBACK;
END;
Output
Added employee...
Employee # : 9601
Name       : FARRELL
Job        : ANALYST
Manager    : 7902
Hire Date  : 03-MAR-08 00:00:00
Salary     : 5000
Commission :
Dept #     : 40
----------------------
Added employee...
Employee # : 9602
Name       : TYLER
Job        : ANALYST
Manager    : 7900
Hire Date  : 25-JAN-08 00:00:00
Salary     : 4800
Commission :
Dept #     : 40
----------------------

The following SELECT command shows that employees Farrell and Tyler were successfully added:

SELECT * FROM emp WHERE empno > 9600;
Output
empno | ename  |  job   | mgr |     hiredate       |   sal   | comm | deptno
------+--------+--------+-----+--------------------+---------+------+--------
  9601| FARRELL| ANALYST|7902 | 03-MAR-08 00:00:00 | 5000.00 |      |   40
  9602| TYLER  | ANALYST|7900 | 25-JAN-08 00:00:00 | 4800.00 |      |   40
(2 rows)

Next, execute the following anonymous block:

BEGIN
    emp_insert(9603,'HARRISON','SALESMAN',7902,'13-DEC-07',5000,3000,20);
    emp_insert(9604,'JARVIS','SALESMAN',7902,'05-MAY-08',4800,4100,11);
    COMMIT;
EXCEPTION
    WHEN OTHERS THEN
        DBMS_OUTPUT.PUT_LINE('SQLERRM: ' || SQLERRM);
        DBMS_OUTPUT.PUT_LINE('An error occurred - roll back inserts');
        ROLLBACK;
END;
Output
Added employee...
Employee # : 9603
Name       : HARRISON
Job        : SALESMAN
Manager    : 7902
Hire Date  : 13-DEC-07 00:00:00
Salary     : 5000
Commission : 3000
Dept #     : 20
----------------------
SQLERRM: insert or update on table "emp" violates foreign key constraint
"emp_ref_dept_fk"
An error occurred - roll back inserts

A SELECT command run against the table produces the following:

SELECT * FROM emp WHERE empno > 9600;
Output
empno | ename  |  job   | mgr |     hiredate       |   sal   | comm | deptno
------+--------+--------+-----+--------------------+---------+------+--------
  9601| FARRELL| ANALYST|7902 | 03-MAR-08 00:00:00 | 5000.00 |      |   40
  9602| TYLER  | ANALYST|7900 | 25-JAN-08 00:00:00 | 4800.00 |      |   40
(2 rows)

The ROLLBACK command in the exception section successfully undoes the insert of employee Harrison. Employees Farrell and Tyler are still in the table as their inserts were made permanent by the COMMIT command in the first anonymous block.

Note

Executing a COMMIT or ROLLBACK in a plpgsql procedure throws an error if an Oracle-style SPL procedure is on the runtime stack.

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