Question

“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：“当我删除得分表中具有subject_id = 1且得分> 8的记录时，exellentEng在类表中将为-1” 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

Answer 1

该行在dbo_score表中将不存在，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伪表，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：正如我在另一个问题上说的那样，如果触发器每次都绝对地计算值，而不是进行求和，则可能会更容易编写和维护这些触发器。然后您可以使用相同的逻辑进行插入，更新和删除，例如像这样：

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

删除触发器不起作用，而添加触发器正常工作吗？

1 个答案: