使用T-SQL合併更新現有記錄並插入不存在但避免重複的記錄

Question

我有兩個具有相同結構t1和t2的表。
表t1比t2有大約100多條記錄。

這裏有一個t1的小樣本。

| pid | tid | amt   | paymentdt | paymentmnth | startdate     | enddate     | updtby 
| 670 | 1  | 690.00  | 2015-07-07 | 2015-07-07 | 2015-10-26 14:36:27.000 | 2015-10-26 15:42:42.000 | NULL 
| 670 | 11  | 855.00  | 2015-07-07 | 2015-07-07 | 2015-10-26 14:36:27.000 | NULL      | NULL 
| 670 | 13  | 129.00  | 2015-07-29 | 2015-07-29 | 2015-10-26 14:36:27.000 | NULL      | NULL 
| 670 | 2  | 855.00  | 2015-09-01 | 2015-09-01 | 2015-10-26 15:42:42.000 | NULL      | NULL 
| Z41 | 1  | 62.35  | 2015-05-08 | 2015-05-08 | 2015-10-26 10:15:24.000 | 2015-10-26 13:08:05.000 | NULL 
| Z41 | 11  | 800.00  | 2015-05-08 | 2015-05-08 | 2015-10-26 10:15:24.000 | NULL      | NULL 
| Z41 | 2  | 298.00  | 2015-06-01 | 2015-06-01 | 2015-10-26 13:08:05.000 | 2015-10-26 14:36:27.000 | NULL 
| Z41 | 3  | 298.00  | 2015-07-01 | 2015-07-01 | 2015-10-26 14:36:27.000 | 2015-10-26 15:15:45.000 | NULL 
| Z41 | 4  | 298.00  | 2015-08-01 | 2015-08-01 | 2015-10-26 15:15:45.000 | 2015-10-26 15:42:42.000 | NULL 
| Z41 | 5  | 238.00  | 2015-09-01 | 2015-09-01 | 2015-10-26 15:42:42.000 | NULL      | NULL 

和t2的小樣本。

| pid | tid | amt   | paymentdt | paymentmnt | startdate     | enddate     | updtby 
| 670 | 1  | 690.00  | 2015-07-07 | 2015-07-07 | 2015-10-02 16:10:50.000 | 2015-10-02 16:35:50.000 | NULL 
| 670 | 11  | 855.00  | 2015-07-07 | 2015-07-07 | 2015-10-02 16:10:50.000 | NULL      | NULL 
| 670 | 13  | 129.00  | 2015-07-29 | 2015-07-29 | 2015-10-02 16:10:50.000 | NULL      | NULL 
| 670 | 2  | 855.00  | 2015-09-01 | 2015-09-01 | 2015-10-02 16:35:50.000 | NULL      | NULL 
| Z41 | 1  | 298.00  | 2015-07-01 | 2015-07-01 | 2015-10-02 16:10:50.000 | 2015-10-02 16:23:26.000 | NULL 
| Z41 | 11  | 800.00  | 2015-05-08 | 2015-05-08 | 2015-10-02 16:10:50.000 | NULL      | NULL 
| Z41 | 2  | 298.00  | 2015-08-01 | 2015-08-01 | 2015-10-02 16:23:26.000 | 2015-10-02 16:35:50.000 | NULL 
| Z41 | 3  | 238.00  | 2015-09-01 | 2015-09-01 | 2015-10-02 16:35:50.000 | NULL      | NULL 
| 173 | 1  | 785.00  | 2015-07-01 | 2015-07-01 | 2015-10-02 16:16:30.000 | 2015-10-02 16:27:36.000 | NULL 
| 173 | 11  | 465.00  | 2015-05-01 | 2015-05-01 | 2015-10-02 16:16:30.000 | NULL      | NULL 

現在比較t1和t2示出了有在T1更多的值的PID Z41如TID的包括1，2，3，4 5，和11，但在t2中僅存在1，2，3 ，和11.

但是，t1和t2之間的startdate是完全不同的，所以這會引發一些問題。下面是我嘗試過的合併，但它基本上只是在t2中插入每行都與t1不同的startdate。

MERGE INTO t2 AS tgt 
USING t1 AS src 
    ON tgt.pid = src.pid AND 
     tgt.tid = src.tid AND 
     tgt.paymentdt = src.paymentdt AND 
     tgt.paymentmnt = src.paymentmnt AND 
     tgt.startdate = src.startdate 
WHEN MATCHED THEN 
    UPDATE SET 
     tgt.amt = src.amt, 
     tgt.paymentdt = src.paymentdt, 
     tgt.updatedby = 'MERGEDUPDATE' 
WHEN NOT MATCHED THEN 
    INSERT (pid, tid, amt, paymentdt, paymentmnt, startdate, enddate, updtby) 
    VALUES (src.pid, src.tid, src.amt, src.paymentdt, src.paymentmnt, src.startdate, src.enddate, 'MERGEDINSERT'); 

有了這個合併我留下的pid and tid其中updtby欄寫着「MERGEDINSERT」重複。但我想避免重複。

如何正確地去了解這個合併不產生重複，但 插入存在於T1而不是T2中的行，同時更新 amt, paymentdt, and paymentmnth值，同時保持STARTDATE？

Answer 1

您描述的方式，您的合併標準應該僅基於pid和tid。試試這個

MERGE INTO t2 AS tgt 
USING t1 AS src 
    ON tgt.pid = src.pid AND 
     tgt.tid = src.tid 

WHEN MATCHED THEN 
    UPDATE SET 
     tgt.amt = src.amt, 
     tgt.paymentdt = src.paymentdt, 
     tgt.paymentmnth = src.paymentmnth, 
     tgt.updatedby = 'MERGEDUPDATE' 
WHEN NOT MATCHED THEN 
    INSERT (pid, tid, amt, paymentdt, paymentmnt, startdate, enddate, updtby) 
    VALUES (src.pid, src.tid, src.amt, src.paymentdt, src.paymentmnt, src.startdate, src.enddate, 'MERGEDINSERT'); 

Answer 2

如果你MERGE，是因爲越來越多條記錄/匹配的拋出一個錯誤，你可以使用子查詢中聚集限制的源表，例如：

;WITH t1cte AS (
    select pid, tid, amt, paymentdt, paymentmnt, startdate, enddate 
    from t1 a 
     inner join (select pid,tid,MAX(paymentdt) as maxdt from t1 group by pid,tid) b 
     on a.pid = b.pid and a.tid = b.tid and a.paymentdt = b.maxdt 
     ) 

MERGE INTO t2 AS tgt 
USING t1cte AS src 
    ON tgt.pid = src.pid AND 
     tgt.tid = src.tid AND 
     tgt.paymentdt = src.paymentdt AND 
     tgt.paymentmnt = src.paymentmnt AND 
     tgt.startdate = src.startdate 
WHEN MATCHED THEN 
    UPDATE SET 
     tgt.amt = src.amt, 
     tgt.paymentdt = src.paymentdt, 
     tgt.updatedby = 'MERGEDUPDATE' 
WHEN NOT MATCHED THEN 
    INSERT (pid, tid, amt, paymentdt, paymentmnt, startdate, enddate, updtby) 
    VALUES (src.pid, src.tid, src.amt, src.paymentdt, src.paymentmnt, src.startdate, src.enddate, 'MERGEDINSERT');