在postgresql中:如何创建一个可以重置的简单计数器？

CREATE SEQUENCE counter_seq;

CREATE TABLE counter (
  id INTEGER PRIMARY KEY DEFAULT NEXTVAL('counter_seq'),
  count INTEGER NOT NULL DEFAULT 0
);

CREATE OR REPLACE FUNCTION update_counter()
RETURNS TRIGGER AS $$
BEGIN
  NEW.count := NEXTVAL('counter_seq');
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER update_counter_trigger
BEFORE INSERT ON counter
FOR EACH ROW
EXECUTE FUNCTION update_counter();

INSERT INTO counter DEFAULT VALUES;

SELECT count FROM counter ORDER BY id DESC LIMIT 1;

ALTER SEQUENCE counter_seq RESTART WITH 1;