--- plpgsql.sgml.orig 2004-12-03 10:01:54.648595360 +1300
+++ plpgsql.sgml 2004-12-03 10:08:58.017297192 +1300
@@ -2556,6 +2556,70 @@
CREATE TRIGGER emp_stamp BEFORE INSERT OR UPDATE ON emp
FOR EACH ROW EXECUTE PROCEDURE emp_stamp();
+
+
+
+
+
+ Another way to log changes to a table involves creating a new table that
+ holds a row for each insert, update, delete that occurs. This approach can
+ be thought of as auditing changes to a table.
+
+
+
+ shows an example of an
+ audit trigger procedure in PL/pgSQL.
+
+
+
+ A PL/pgSQL Trigger Procedure For Auditing
+
+
+ This example trigger ensures that any insert, update or delete of a row
+ in the emp table is recorded (i.e. audited) in the emp_audit table.
+ The current time and user name are stamped into the row, together with
+ the type of operation performed on it.
+
+
+
+CREATE TABLE emp (
+ empname text NOT NULL,
+ salary integer
+);
+
+CREATE TABLE emp_audit(
+ operation char(1) NOT NULL,
+ stamp timestamp NOT NULL,
+ userid text NOT NULL,
+ empname text NOT NULL,
+ salary integer
+);
+
+CREATE OR REPLACE FUNCTION process_emp_audit() RETURNS TRIGGER AS $emp_audit$
+ BEGIN
+ --
+ -- Create a row in emp_audit to reflect the operation performed on emp,
+ -- make use of the special variable TG_OP to work out the operation.
+ --
+ IF (TG_OP = 'DELETE') THEN
+ INSERT INTO emp_audit SELECT 'D', now(), user, OLD.*;
+ RETURN OLD;
+ ELSIF (TG_OP = 'UPDATE') THEN
+ INSERT INTO emp_audit SELECT 'U', now(), user, NEW.*;
+ RETURN NEW;
+ ELSIF (TG_OP = 'INSERT') THEN
+ INSERT INTO emp_audit SELECT 'I', now(), user, NEW.*;
+ RETURN NEW;
+ END IF;
+ END;
+$emp_audit$ language plpgsql;
+
+
+CREATE TRIGGER emp_audit
+AFTER INSERT OR UPDATE OR DELETE ON emp
+ FOR EACH ROW EXECUTE PROCEDURE process_emp_audit()
+;
+