create table ab ( id int, changetimestamp timestamp  NOT NULL  default CURRENT_TIMESTAMP  on update CURRENT_TIMESTAMP);

create or replace function upd_timestamp() returns trigger as$$begin  new.modified = current_timestamp;  return new;end$$language plpgsql;drop table if exists ts;create table ts (  id   bigserial primary key,  tradeid integer ,  email varchar(50),  num integer,  modified timestamp default current_timestamp);create trigger t_name before update on ts for each row execute procedure upd_timestamp();

insert into ts (tradeid,email,num) values (1223,'mike_zhang@live.com',1);update ts set email='Mike_Zhang@live' where tradeid = 1223 ;create unique index ts_tradeid_idx on ts(tradeid);insert into ts(tradeid,email,num) values (1223,'Mike_Zhang@live.com',2) on conflict(tradeid) do updateset email = excluded.email,num=excluded.num;select * from ts;-- delete from ts;