Question

现在我写的触发器有以下问题：如果我插入的新行与表weeklymeeting中的一个条目冲突，它不应该插入表并给我错误消息。如果NEW行不与表冲突，则新行应插入表中。但是下面的代码在时间冲突时，它会在不冲突时给我错误，它不能在表中插入新行。以下触发器的问题在哪里？如何解决这个问题？

    DROP FUNCTION IF EXISTS time_conflict() CASCADE;
create or replace function time_conflict() 
returns trigger as 
$BODY$
begin   
    if exists(  
        select *
        from weeklymeeting d

        where NEW.section_id=d.section_id 
        AND NEW.weekday= d.weekday 
        AND ((d.starttime <= NEW.starttime AND d.endtime > NEW.starttime) OR (d.starttime < NEW.endtime AND d.endtime >= NEW.endtime) OR (d.starttime >=NEW.starttime AND d.endtime <=NEW.endtime )) 
        )THEN
           RAISE EXCEPTION 'SAME section time conflict!';
        else
        INSERT INTO weeklymeeting VALUES (NEW.*); 
        end if; 
        RETURN NEW;

end;
$BODY$
    LANGUAGE plpgsql;

CREATE TRIGGER time_conflict
BEFORE INSERT ON weeklymeeting for each ROW
EXECUTE PROCEDURE time_conflict();

根据BjörnNilsson的评论我的问题已解决。正确的解决方案将是：

DROP FUNCTION IF EXISTS time_conflict() CASCADE;
create or replace function time_conflict() 
returns trigger as 
$BODY$
begin   
    if exists(  
        select *
        from weeklymeeting d

        where NEW.section_id=d.section_id 
        AND NEW.weekday= d.weekday 
        AND ((d.starttime <= NEW.starttime AND d.endtime > NEW.starttime) OR (d.starttime < NEW.endtime AND d.endtime >= NEW.endtime) OR (d.starttime >=NEW.starttime AND d.endtime <=NEW.endtime )) 
        )THEN
           RAISE EXCEPTION 'SAME section time conflict!';

        end if; 
        RETURN NEW;

end;
$BODY$
    LANGUAGE plpgsql;

CREATE TRIGGER time_conflict
BEFORE INSERT ON weeklymeeting for each ROW
EXECUTE PROCEDURE time_conflict();

Answer 1

无需触发器：

ALTER TABLE weeklymeeting ADD CONSTRAINT section_weekday_unique_constraint UNIQUE (section, weekday);

这会在这两列上创建索引，因此您可能希望颠倒它们的顺序，具体取决于您查询数据的方式

postgresql触发器插入

1 个答案: