更新和Liquibase YAML:

databaseChangeLog:
  - changeSet:
      id: CREATE FUNCTION set_now_to_timestamp
      author: Konstantin Chvilyov
      changes:
        - sql:
            sql: CREATE OR REPLACE FUNCTION set_now_to_timestamp() RETURNS TRIGGER LANGUAGE plpgsql AS 'BEGIN NEW.timestamp = NOW(); RETURN NEW; END;'

  - changeSet:
      id: CREATE TRIGGER update_users_set_now_to_timestamp
      author: Konstantin Chvilyov
      changes:
        - sql:
            sql: CREATE TRIGGER update_users_set_now_to_timestamp BEFORE UPDATE ON users FOR EACH ROW EXECUTE PROCEDURE set_now_to_timestamp();

更新和Liquibase YAML:

databaseChangeLog:
  - changeSet:
      id: CREATE FUNCTION set_now_to_timestamp
      author: Konstantin Chvilyov
      changes:
        - sql:
            sql: CREATE OR REPLACE FUNCTION set_now_to_timestamp() RETURNS TRIGGER LANGUAGE plpgsql AS 'BEGIN NEW.timestamp = NOW(); RETURN NEW; END;'

  - changeSet:
      id: CREATE TRIGGER update_users_set_now_to_timestamp
      author: Konstantin Chvilyov
      changes:
        - sql:
            sql: CREATE TRIGGER update_users_set_now_to_timestamp BEFORE UPDATE ON users FOR EACH ROW EXECUTE PROCEDURE set_now_to_timestamp();

要在插入新行时自动更新PostgresSQL中的时间戳字段，可以将current_timestamp设置为默认值:

CREATE TABLE users (
    id serial not null,
    firstname varchar(100),
    middlename varchar(100),
    lastname varchar(100),
    email varchar(200),
    timestamp timestamp default current_timestamp
)

除此之外，你可能想要阻止任何人在未来更新这个字段，这可以通过创建一个更新触发器并应用它来完成:

CREATE OR REPLACE FUNCTION stop_change_on_timestamp()
  RETURNS trigger AS
$BODY$
BEGIN
  -- always reset the timestamp to the old value ("actual creation time")
  NEW.timestamp := OLD.timestamp;
  RETURN NEW;
END;
$BODY$

CREATE TRIGGER prevent_timestamp_changes
  BEFORE UPDATE
  ON users
  FOR EACH ROW
  EXECUTE PROCEDURE stop_change_on_timestamp();

仅在值更改时更新时间戳

基于E.J的链接，并从这个链接中添加一个if语句(https://stackoverflow.com/a/3084254/1526023)

CREATE OR REPLACE FUNCTION update_modified_column()
RETURNS TRIGGER AS $$
BEGIN
   IF row(NEW.*) IS DISTINCT FROM row(OLD.*) THEN
      NEW.modified = now(); 
      RETURN NEW;
   ELSE
      RETURN OLD;
   END IF;
END;
$$ language 'plpgsql';

使用'now()'作为默认值自动生成时间戳。

您需要编写一个插入触发器，如果您希望在记录更改时更改它，则可能需要编写一个更新触发器。这篇文章解释得很好:

http://www.revsys.com/blog/2006/aug/04/automatically-updating-a-timestamp-column-in-postgresql/

update_modified_column() 返回触发器为$$ 开始 新的。Modified = now(); 返回新; 结束; $$ language 'plpgsql'; 像这样应用触发器: EXECUTE PROCEDURE update_modified_column();