MERGE 語句 SQL 有幾個條件

Question

我有看起來像這樣的數據，我似乎無法弄清楚如何讓 MERGE 語句工作，因為它的條件有限：

進行合並時，除清除記錄外，一切正常

資源：

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)

目標：

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

有什么想法嗎？

Answer 1

如果我正確理解您的問題，那么您想使用以下條件：

• 當與目標不匹配時
• 當與源不匹配時

一個粗略的例子：

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;

參考： MERGE (Transact-SQL)