Question

我有一个带有Deleted标志（bit）列的表格。怎么可能实现呢？

在以下条件下列：

如果记录是新的或更新的，请设置为1
如果从源中删除，请设为0

我认为可以在合并声明中进行。但我不知道该怎么做。或许还有另一种方式？

Answer 1

我认为您可以使用合并语句来执行此操作：

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

这将在目标表中插入任何不存在的行。这将更新目标中的任何匹配行和任何行，但源不会更新为1。

Answer 2

您可能需要仔细检查您的要求，因为Deleted标记的标准为0表示未删除，1表示已删除。 0为false，1为真。事实上，这是如此常见，我只是假设这就是你想要的。

至于使用MERGE进行设置，您需要执行以下操作：

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 */);

删除表中的标志

2 个答案: