删除触发器不起作用而添加触发器正常工作?

Delete trigger doesn't work while add trigger work correctly?

删除触发器不起作用,而添加触发器正常工作。

它应该像这样工作:"When I delete a record in score table that has subject_id = 1 and score > 8, exellentEng will -1 in class table" 我不知道为什么。帮帮我

ALTER TRIGGER [dbo].[deleteExellentEnglishStudent]
ON [dbo].[dbo_score]
AFTER DELETE AS 
    BEGIN
      UPDATE x SET
        exellent_Eng -=1
      FROM dbo.dbo_class x
      JOIN dbo.dbo_student s ON s.class_id = x.class_id
      JOIN dbo.dbo_score c ON c.student_id = s.student_id
      WHERE (c.subject_id = 1 AND c.score >= 8)
      and c.score_id in (SELECT Deleted.score_id FROM Deleted)
    END
ALTER TRIGGER [dbo].[addExellentEnglishStudent] ON [dbo].[dbo_score]
    AFTER INSERT AS 
    BEGIN
      UPDATE x SET
        exellent_Eng += 1
      FROM dbo.dbo_class x
      JOIN dbo.dbo_student s ON s.class_id = x.class_id
      JOIN dbo.dbo_score c ON c.student_id = s.student_id
      WHERE (c.subject_id = 1 AND c.score >= 8)
      AND c.score_id IN
      (select Inserted.score_id from Inserted)
    END

该行将不存在于 dbo_score table 中,因为它是一个 after 触发器,因此该行已被删除。而是直接使用 Deleted 伪 table 例如

ALTER TRIGGER [dbo].[deleteExellentEnglishStudent]
ON [dbo].[dbo_score]
AFTER DELETE AS 
BEGIN
  UPDATE x SET
    exellent_Eng -=1
  FROM dbo.dbo_class x
  JOIN dbo.dbo_student s ON s.class_id = x.class_id
  JOIN dbo.Deleted c ON c.student_id = s.student_id
  WHERE (c.subject_id = 1 AND c.score >= 8)
END

注意:正如我在您的其他问题中所说的那样,您可能会发现,如果它们每次都计算绝对值而不是处理差异,那么编写和维护这些触发器会更容易。然后您可以使用相同的逻辑进行插入、更新和删除,例如类似于:

ALTER TRIGGER [dbo].[deleteExellentEnglishStudent]
ON [dbo].[dbo_score]
AFTER INSERT, UPDATE, DELETE
AS 
BEGIN
  UPDATE x SET
    exellent_Eng = (select count(*) from dbo.dbo_score where c.subject_id = 1 AND c.score >= 8)
  FROM dbo.dbo_class x
  JOIN dbo.dbo_student s ON s.class_id = x.class_id
  where S.studentid in (select student_id from Inserted union all select student_id from Deleted)
END