Postgres 13

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
CREATE TABLE public.emp(
  empname TEXT NOT NULL,
  salary INTEGER
);

CREATE TABLE public.emp_audit(
  operation CHAR(1) NOT NULL,
  stamp TIMESTAMP NOT NULL,
  userid TEXT NOT NULL,
  empname TEXT NOT NULL,
  salary INTEGER
);
CREATE FUNCTION public.audit() RETURNS TRIGGER AS $$ 
DECLARE 
  tbname TEXT := (string_to_array(tg_argv[0],'.'))[1];
  schname TEXT := (string_to_array(tg_argv[0],'.'))[2];
BEGIN
EXECUTE format('INSERT INTO %I.%I SELECT ''I'', current_timestamp, %L, ($1::%I.%I).*', 
  tbname,schname,CURRENT_USER,tg_table_schema,tg_table_name ) USING NEW;
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER emp_audit_trig AFTER INSERT OR UPDATE OR DELETE
ON public.emp FOR EACH ROW EXECUTE FUNCTION public.audit('public.emp_audit');
INSERT INTO public.emp VALUES ('foo',42);
SELECT * FROM public.emp;
1 rows affected



empname
salary


foo
42


SELECT * FROM public.emp_audit;


operation
stamp
userid
empname
salary


I
2021-03-24 08:28:58.477075
u_859491768
foo
42