Does SQL Server Offer Anything Like MySQL's ON

Question

In MySQL, if you specify ON DUPLICATE KEY UPDATE and a row is inserted that would cause a duplicate value in a UNIQUE index or PRIMARY KEY, an UPDATE of the old row is performed. For example, if column a is declared as UNIQUE and contains the value 1, the following two statements have identical effect:

INSERT INTO table (a,b,c) VALUES (1,2,3)
  ON DUPLICATE KEY UPDATE c=c+1;

UPDATE table SET c=c+1 WHERE a=1;

I don't believe I've come across anything of the like in T-SQL. Does SQL Server offer anything comparable to MySQL's ON DUPLICATE KEY UPDATE?

Answer 1

There's no DUPLICATE KEY UPDATE equivalent, but MERGE and WHEN MATCHED might work for you

Inserting, Updating, and Deleting Data by Using MERGE

Answer 2

I was surprised that none of the answers on this page contained an example of an actual query, so here you go:

A more complex example of inserting data and then handling duplicate

MERGE
INTO MyBigDB.dbo.METER_DATA WITH (HOLDLOCK) AS target
USING (SELECT
    77748 AS rtu_id
   ,'12B096876' AS meter_id
   ,56112 AS meter_reading
   ,'20150602 00:20:11' AS local_time) AS source
(rtu_id, meter_id, meter_reading, time_local)
ON (target.rtu_id = source.rtu_id
  AND target.time_local = source.time_local)
WHEN MATCHED
  THEN UPDATE
      SET meter_id = '12B096876'
         ,meter_reading = 56112
WHEN NOT MATCHED
  THEN INSERT (rtu_id, meter_id, meter_reading, time_local)
      VALUES (77748, '12B096876', 56112, '20150602 00:20:11');

Answer 3

SQL server 2000 onwards has a concept of instead of triggers, which can accomplish the wanted functionality - although there will be a nasty trigger hiding behind the scenes.

Check the section "Insert or update?"

http://msdn.microsoft.com/en-us/library/aa224818(SQL.80).aspx

Answer 4

SQL Server 2008 has this feature, as part of TSQL.
See documentation on MERGE statement here - http://msdn.microsoft.com/en-us/library/bb510625.aspx