1.

CREATE [ OR REPLACE ] RULE name AS ON event

TO table_name [ WHERE condition ]

DO [ ALSO | INSTEAD ] { NOTHING | command | ( command ; command ... ) }

2.

CREATE  TRIGGER trigger_name [BEFORE|AFTER|INSTEAD OF] event_name

ON table_name

[

 -- Trigger logic goes here....

];  

3.

CREATE [OR REPLACE] FUNCTION function_name (arguments)

RETURNS return_datatype AS $variable_name$

  DECLARE

    declaration;

    [...]

  BEGIN

    < function_body >

    [...]

    RETURN { variable_name | value }

  END; LANGUAGE plpgsql;