Oracle example of autonomous transaction for logging audit messages

autonomous_audit.sql

-- 1) Create a table in the hr database called 'log'
-- with two fields; log_msg (text) and time_of_msg (datetime)

-- 2) Modify the procedure below to insert a record into
-- the log table;
CREATE OR REPLACE PROCEDURE hr.log_details (msg IN VARCHAR2)
IS
PRAGMA AUTONOMOUS_TRANSACTION; -- run a commit here regardless of any other transaction state
BEGIN
    INSERT INTO hr.log(msg_id,log_msg,time_of_msg)
    VALUES(log_seq.NEXTVAL,msg,SYSDATE);
    COMMIT; -- must commit or rollback in an autonomous_transaction
END;

-- 3) Run the following statement and see what the 'employees' table
-- and the 'log' table look like afterwards.
BEGIN
    DELETE hr.employees;
    log_msg('Deleting all employees');
    ROLLBACK;
    log_msg('after rollback of delete employees');
END;