MERGE 语句 SQL 有几个条件

Question

我有看起来像这样的数据，我似乎无法弄清楚如何让 MERGE 语句工作，因为它的条件有限：

进行合并时，除清除记录外，一切正常

资源：

AccountID = 123, Name = Mike, Balance = 100 (This should result in UPDATE - Matched Condition)
AccountID = 234, Name = Smith, Balance = 50 (This should result in New - Not Matched Condition)

目标：

AccountID = 123, Name = Mike, Balance = 150
AccountID = 12345, Name = john, Balance = 200 (This record needs to be marked as purged)

有什么想法吗？

Answer 1

如果我正确理解您的问题，那么您想使用以下条件：

• 当与目标不匹配时
• 当与源不匹配时

一个粗略的例子：

merge ExistingTable as dest
using   ( values 
             ('123','Mike', '100')
            ,('234','Smith', '50')
        ) as src([AccountID], [Name], [Balance] )
    on src.[AccountID] = dest.[AccountID]
when matched then
    update set
        [Name] = src.[Name],
        [Balance] = src.[Balance]
when not matched by target then 
    insert ([AccountID],[Name],[Balance])
        values (src.[AccountID],src.[Name],src.[Balance])
when not matched by source then
    delete;

参考： MERGE (Transact-SQL)