SQL触发器更新另一个表

问题将与EMAIL表上缺少主键有关。触发器与不变的主键配合使用效果最佳。

另外，如果某行变为非主要行，您该如何从PERSON中删除该条目？

因此，在问题域中似乎仍然存在一些悬而未决的问题，但这是对触发器的外观的一种刺探。您可以添加一些东西来查找实际发生更改的行-但要注意NULL。

CREATE TRIGGER EMAIL_update ON UPDATEASBEGIN    UPDATE PERSON    SET EMAIL = i.EMAILADDRESS        FROM PERSON    INNER JOIN inserted AS i        ON i.PERSonID = PERSON.PERSonID    INNER JOIN deleted AS d -- could try changing this to a left join and use same trigger for INSERT        ON -- what? could use PERSONID, but it's not unique    WHERe i.ISPRIMARY = 1 -- This helps with uniqueness, but what about things leaving primary?    -- AND i.EMAILADDRESS <> PERSON.EMAIL -- Could add this (what about NULLs?)END