表中的已刪除標記

Question

我有一個表，其中Deleted標記（bit）列。如何才能實現它？

在此列以下條件：

• 如果記錄是新的或更新，設置爲1

• 如果從源中刪除，設置爲0

我想可以在合併聲明中做出。但我不知道該怎麼做。或者也許有另一種方式？

Answer 1

我想你可以使用一個MERGE語句來做到這一點：

merge into myTable using SourceTable 
on myTable.pk = sourcetable.pk  
when matched then update set 
/*add any update columns here*/ 
Deleted = 0  
when not matched by target then insert 
(pk, abcd, deleted) 
values 
(pk, xyz, 0) 
when not matched by source then update set Deleted = 1 

這將插入不存在到目標表中的所有行。這將更新目標相匹配的任何行和任何行，但不是源將有標誌更新爲1

Answer 2

您可能要仔細檢查你的要求，因爲對於一個Deleted標誌的規範將是0不刪除和1已刪除。 0是錯誤的，並且1爲真。事實上，這很常見，我只是假設這就是你想要的。

至於有MERGE設置它，你會想要做的事，如：

MERGE MyTable as Target 
USING YourTable as Source ON 
    Target.Id = Source.Id 
WHEN MATCHED THEN 
    --Exists in both Source and Target 
    UPDATE SET Deleted = 0 /* include other columns to update here */ 
WHEN NOT MATCHED BY Source THEN 
    --Source was deleted 
    UPDATE SET Deleted = 1 
WHEN NOT MATCHED BY Target THEN 
    --Source was added 
    INSERT (Id, Deleted /* include other columns to insert here */) 
    VALUES (Source.Id, 1 /* include other columns to insert here */);