Question

我向触发器FOR UPDATE添加了两个update语句，但是该列不会更新，不确定我做错了什么。请参见下面两个语句的示例。

表Relationship

 Update Profile 
 Set LDR = 1
 From inserted, Profile
 Where inserted.TARGET_ID = profile.ID  
   And inserted.RELATION_TYPE = 'LEADER'

 Update Profile
 Set LDR = 0
 From Deleted, Profile
 Where Deleted.Target_ID = profile.ID 
   And Deleted.RELATION_TYPE = 'LEADER'

个人资料表：

  ID      | LDR |
  --------+-----+
  4658632 |  0  |

关系表：

TARGET_ID | Relation_TYPE
----------+--------------
 4658632  | LEADER

如果在关系表中插入一条记录，其中Relation_TYPE等于LEADER，则将配置文件表列LDR更新为1。反之亦然。

有什么遗漏吗？

谢谢

Answer 1

最好这样写：（编辑）

update 
    p
set
    LDR = case profile.ID when inserted.TARGET_ID then 1 else 0 end
from 
    Profile p
    left join inserted i on
        i.TARGET_ID = p.ID  
    left join deleted d on
        d.TARGET_ID = p.ID
where
    (
        i.RELATION_TYPE = 'LEADER' or
        d.RELATION_TYPE = 'LEADER'
    );

或更安全的方法来确保更新的内容没有歧义：

with cte
as  (
    select
        ID,
        [LDR] = 1
    from
        Profile p
        inner join inserted i on
            i.TARGET_ID = p.ID
    where
        i.RELATION_TYPE = 'LEADER'
        union all
    select
        ID,
        [LDR] = 0
    from
        Profile p
        inner join deleted d on
            d.TARGET_ID = p.ID
    where
        d.RELATION_TYPE = 'LEADER'
    )
update
    p
set
    LDR = cte.LDR
from
    Profile p
    inner join cte on 
        p.ID = cte.ID;

Answer 2

缺少条件测试。如果它们在同一UPDATE触发器中，则在实际更新记录时，已插入和已删除中都会有值。要解决此问题，请尝试：

WITH Updates AS (
    SELECT IsNull(i.Target_ID, d.Target_ID) as Target_ID,
    CASE
        WHEN i.Target_ID IS NULL
            THEN 0
        ELSE 1
    END as value
    FROM (
        SELECT Target_ID
        FROM inserted
        WHERE RELATION_TYPE = 'LEADER'
        ) as i

    FULL OUTER JOIN (
        SELECT Target_ID
        FROM deleted
        WHERE RELATION_TYPE = 'LEADER'
        ) as d
    ON i.Target_ID = d.Target_ID
    ) u
Update Profile 
    Set LDR = value
FROM Profile p
INNER JOIN Updates u
    ON p.Target_ID = u.Target_ID

更新触发器不会触发两个语句

2 个答案: