插入SQL触发器，删除2个表格

Question

我有2个表格称为患者和诊断。如下

 
Patient  Diagnosis 
---------  ------------ 
ID (PK)  ID (PK) 
Name   PatientID (FK: Reference to Patient => ID) 
Status 
******   ***** 
----------  ----------- 

在此，患者状态可以是[注册，诊断和OnCourse]

期间，

• 新患者插入，患者状态将是注册
• 新诊断I nsert，患者状态将诊断

现在， 诊断删除，我需要检查，如果患者在诊断表至少一个诊断条目，那么患者状态会诊断否则注册

所以，如何做到单触发所有这些条件？

请帮帮我。

Answer 1

触发器根据诊断表上的INSERT和DELETE更新Patient.Status。

CREATE TRIGGER dbo.Diagnosis_TrgInsDel 
    ON dbo.Diagnosis 
    AFTER DELETE, INSERT 
AS 
BEGIN 

    -- SET NOCOUNT ON added to prevent extra result sets from 
    -- interfering with SELECT statements. 
    SET NOCOUNT ON; 


    -- Change the Status to 'Registered' after the last 
    -- Diagnosis record is deleted 
    -------------------------------------------------------------------------------- 
    UPDATE 
     Patient 
    SET 
     [Status] = 'Registered' 
    FROM 
     Patient 
    INNER JOIN 
     Deleted 
     ON Deleted.PatientID = Patient.ID 
    WHERE 
     NOT EXISTS (SELECT * FROM Diagnosis WHERE PatientID = Deleted.PatientID) 


    -- Change the Status to 'Diagnosed' after an Insert and the 
    -- current Status is 'Registered' 
    -------------------------------------------------------------------------------- 
    UPDATE 
     Patient 
    SET 
     [Status] = 'Diagnosed' 
    FROM 
     Patient 
    INNER JOIN 
     Inserted 
     ON Inserted.PatientID = Patient.ID 
    WHERE 
     Patient.[Status] = 'Registered' 

END 

我实际上不会将此作为两个触发器。一个用于AFTER DELETE，另一个用于AFTER INSERT。这意味着当存在INSERT时，DELETE代码不会运行，反之亦然。但是上面的代码确实可以正常工作。

EDIT

AS通过尼古拉斑点;如果插入或更新多个诊断，在相同的操作中，对于同一患者，则这可能会多次更新单个患者记录。这些修改应该解决...

UPDATE 
     Patient 
    SET 
     [Status] = 'Registered' 
    WHERE 
     NOT EXISTS (SELECT * FROM Diagnosis WHERE PatientID = Patient.ID) 
     AND EXISTS (SELECT * FROM Deleted WHERE PatientID = Patient.ID) 

而且......

UPDATE 
     Patient 
    SET 
     [Status] = 'Diagnosed' 
    WHERE 
      Patient.[Status] = 'Registered' 
     AND EXISTS (SELECT * FROM Inserted WHERE PatientID = Patient.ID) 

Answer 2

在第一部分，你可以简单地添加默认约束：

alter table patient add constraint df_status default 'Registered' for status 

如果这是不够的，因为你的前端是不能在插入省略状态或设定值设为默认，你可以创建一个触发：

create trigger PatientInsertTrigger on patient 
after insert 
as 
    -- trigger should not alter @@rowcount 
    set nocount on 

    update patient 
     set status = 'Registered' 
    from Patient 
    -- Inserted is a pseudotable holding newly inserted rows 
    -- This is how we know what records to update 
    inner join Inserted 
     on Patient.ID = Inserted.ID 

当记录添加到诊断或从诊断中删除时，应根据诊断中匹配记录的数量更新患者状态。幸运的是，在调用触发器的时候，记录已经在表中了，所以在这两种情况下都需要count（）。

create trigger DiagnosisTrigger on diagnosis 
after insert, delete 
as 
    set nocount on 

    update patient 
     set status = case when d.NumberOfDiagnosis <> 0 
         then 'Diagnosed' 
         else 'Registered' 
        end 
    from Patient 
    inner join 
    (
     select PatientID, count(*) NumberOfDiagnosis 
     from Diagnosis 
     -- Get all patients with added or removed diagnosis 
     where PatientID in (select PatientID 
          from Inserted 
          union 
          select PatientID 
          -- Pseudotable holding removed records 
          from Deleted) 
     group by PatientID 
    ) d 
     on Patient.ID = d.PatientID 

状态应该是StatusID，但是您没有提到适当的id号。