SQL Сервер - MERGE: MATCHED Два обновления - второе обновление на основе записей из первого обновления в той же таблице

Question

Ищем журнал запросов c в операторе MERGE

MERGE <statement>

WHEN MATCHED 
 UPDATE active=1, value='testnew' where field='1200' and id=4
 UPDATE active=0 where field='1200' and id <> 4 --This update is based on first update 

WHEN UNMATCHED <statement>

До MERGE;

id  field   value   active  
--------------------------
1   1200    hai     1   
2   1200    hello   1   
3   1200    hi      1   
4   1200    test    1   

После MERGE:

id  field   value   active  
----------------------------
1   1200    hai     0       --Update active=0  for all other records with same field =1200
2   1200    hello   0       --Update active=0  for all other records with same field =1200
3   1200    hi      0       --Update active=0  for all other records with same field =1200
4   1200    testnew 1       --MATCHED CASE id=4, UPDATE value

Answer 1

Вы можете попробовать это:

MERGE <statement>

WHEN MATCHED THEN
 UPDATE SET active = CASE WHEN field = '1200' and id = 4 THEN 1
                          WHEN field = '1200' and id <> 4 THEN 0
                          ELSE target.active
                     END
            value = CASE WHEN field = '1200' and id = 4 THEN 'testnew' 
                         ELSE target.value
                     END