Mega Code Archive
The use of a trigger
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SQL>
SQL> set feedback on
SQL> set pages 9999 serveroutput on size 1000000
SQL>
SQL> CREATE TABLE authors (
2 id NUMBER PRIMARY KEY,
3 first_name VARCHAR2(50),
4 last_name VARCHAR2(50)
5 );
Table created.
SQL>
SQL> INSERT INTO authors (id, first_name, last_name)
2 VALUES (1, 'Marlene', 'Theriault');
1 row created.
SQL>
SQL> INSERT INTO authors (id, first_name, last_name)
2 VALUES (2, 'Rachel', 'Carmichael');
1 row created.
SQL>
SQL> INSERT INTO authors (id, first_name, last_name)
2 VALUES (3, 'James', 'Viscusi');
1 row created.
SQL>
SQL> INSERT INTO authors (id, first_name, last_name)
2 VALUES (4, 'Michael', 'Abbey');
1 row created.
SQL>
SQL> INSERT INTO authors (id, first_name, last_name)
2 VALUES (5, 'Michael', 'Corey');
1 row created.
SQL>
SQL> INSERT INTO authors (id, first_name, last_name)
2 VALUES (6, 'Scott', 'Urman');
1 row created.
SQL>
SQL> INSERT INTO authors (id, first_name, last_name)
2 VALUES (7, 'Ron', 'Hardman');
1 row created.
SQL>
SQL> INSERT INTO authors (id, first_name, last_name)
2 VALUES (8, 'Mike', 'McLaughlin');
1 row created.
SQL>
SQL> COMMIT;
Commit complete.
SQL>
SQL> SELECT id, first_name, last_name
2 FROM authors
3 WHERE last_name = 'HARDMAN';
no rows selected
SQL>
SQL> CREATE OR REPLACE TRIGGER author_trig
2 AFTER UPDATE OF first_name
3 ON authors
4 FOR EACH ROW
5 WHEN (OLD.first_name != NEW.first_name)
6 BEGIN
7 DBMS_OUTPUT.PUT_LINE('First Name '
8 ||:OLD.first_name
9 ||' has change to '
10 ||:NEW.first_name);
11 END;
12 /
Trigger created.
SQL>
SQL> UPDATE authors
2 SET first_name = 'Ronald'
3 WHERE first_name = 'Ron';
First Name Ron has change to Ronald
1 row updated.
SQL>
SQL> drop table authors;
Table dropped.
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