-- TRIGGER
CREATE TABLE test_tbl (i integer, s text);
ERROR:  relation "test_tbl" already exists
CREATE FUNCTION test_trigger() RETURNS trigger AS
$$
	pljs.elog(NOTICE, "NEW = ", JSON.stringify(NEW));
	pljs.elog(NOTICE, "OLD = ", JSON.stringify(OLD));
	pljs.elog(NOTICE, "TG_OP = ", TG_OP);
	pljs.elog(NOTICE, "TG_ARGV = ", TG_ARGV);
	if (TG_OP == "UPDATE") {
		NEW.i = 102;
		return NEW;
	}

	return NEW;
$$
LANGUAGE pljs;
CREATE TRIGGER test_trigger
  BEFORE INSERT OR UPDATE OR DELETE
  ON test_tbl FOR EACH ROW
  EXECUTE PROCEDURE test_trigger();
INSERT INTO test_tbl VALUES(100, 'ABC');
NOTICE:  NEW =  {"i":100,"s":"ABC"}
NOTICE:  OLD =  undefined
NOTICE:  TG_OP =  INSERT
NOTICE:  TG_ARGV =  
UPDATE test_tbl SET i = 101, s = 'DEF' WHERE i = 1;
NOTICE:  NEW =  {"i":101,"s":"DEF"}
NOTICE:  OLD =  {"i":1,"s":"s1"}
NOTICE:  TG_OP =  UPDATE
NOTICE:  TG_ARGV =  
DELETE FROM test_tbl WHERE i >= 100;
NOTICE:  NEW =  undefined
NOTICE:  OLD =  {"i":100,"s":"ABC"}
NOTICE:  TG_OP =  DELETE
NOTICE:  TG_ARGV =  
NOTICE:  NEW =  undefined
NOTICE:  OLD =  {"i":102,"s":"DEF"}
NOTICE:  TG_OP =  DELETE
NOTICE:  TG_ARGV =  
SELECT * FROM test_tbl;
 i | s  
---+----
 2 | s2
 3 | s3
 4 | s4
(3 rows)

-- One more trigger
CREATE FUNCTION test_trigger2() RETURNS trigger AS
$$
	var tuple;
	switch (TG_OP) {
	case "INSERT":
		tuple = NEW;
		break;
	case "UPDATE":
		tuple = OLD;
		break;
	case "DELETE":
		tuple = OLD;
		break;
	default:
		return;
	}
	if (tuple.subject == "skip") {
		return null;
	}
	if (tuple.subject == "modify" && NEW) {
		NEW.val = tuple.val * 2;
		return NEW;
	}
$$
LANGUAGE pljs;
CREATE TABLE trig_table (subject text, val int);
INSERT INTO trig_table VALUES('skip', 1);
CREATE TRIGGER test_trigger2
  BEFORE INSERT OR UPDATE OR DELETE
  ON trig_table FOR EACH ROW
  EXECUTE PROCEDURE test_trigger2();
INSERT INTO trig_table VALUES
  ('skip', 1), ('modify', 2), ('noop', 3);
SELECT * FROM trig_table;
 subject | val 
---------+-----
 skip    |   1
 modify  |   4
 noop    |   3
(3 rows)

UPDATE trig_table SET val = 10;
SELECT * FROM trig_table;
 subject | val 
---------+-----
 skip    |   1
 modify  |   8
 noop    |  10
(3 rows)

DELETE FROM trig_table;
SELECT * FROM trig_table;
 subject | val 
---------+-----
 skip    |   1
(1 row)