Question

我有一个看起来像这样的触发器：

CREATE OR REPLACE FUNCTION CHECK_SCHEDULE()
RETURNS TRIGGER AS
$BODY$
BEGIN
  IF EXISTS(
    SELECT DAY, TIME FROM MEETING
    WHERE NEW.DAY = MEETING.DAY AND NEW.TIME > MEETING.TIME
    ) THEN
    RAISE EXCEPTION 'THERE IS A MEETING HAPPENING ON % % ', NEW.DAY, NEW.TIME;
  ELSE
    RETURN NEW;
  END IF;
END;
$BODY$ LANGUAGE PLPGSQL;

这很好用，除非我希望消息与它冲突的时间：在MEETING.DAY和MEETING.TIME 上发生了一次会议。

但是我不能这样做，因为它不知道这些变量是什么。是否可以将值存储在我的select子句中，以便以后可以使用它们？

Answer 1

您可以将day和time移动到声明的变量（例如RECORD）以供日后参考。

CREATE OR REPLACE FUNCTION CHECK_SCHEDULE()
RETURNS TRIGGER AS
$BODY$
DECLARE

    meetinginfo RECORD;

BEGIN

    SELECT meeting.day, meeting.time
    INTO meetinginfo
    FROM meeting
    WHERE new.day = meeting.day
    AND new.time > meeting.time
    ORDER BY new.time
    LIMIT 1;

    IF FOUND THEN
        RAISE EXCEPTION 'THERE IS A MEETING HAPPENING ON % %', meetinginfo.day, meetinginfo.time;
    END IF;

    RETURN NEW;

END;
$BODY$ LANGUAGE plpgsql;

如何在触发PostgreSQL中存储值

1 个答案: