噢~哟~哟——每天进步一点点o-u-u

mysql在处理唯一主键记录时可以一个语句实现没有记录时插入有记录时更新， 只要使用“insert …… on duplicate key update …. ”，非常简洁高效，oracle 、 DB2 都有类似的语法可以实现相同的功能，但坑爹的是sql server没有对应的语句，但可以使用下面的语句实现相同的功能，但稍许复杂些：

• 1. 对于sql server 2008及以后的版本，可以使用merge语法， 可以参考下面的实例用法：

CREATE TABLE #mytable(COL_A VARCHAR(10), COL_B VARCHAR(10), COL_C VARCHAR(10), COL_D VARCHAR(10))
INSERT INTO #mytable VALUES('1','0.1', '0.2', '0.3'); --<These are the values we'll be updating
SELECT * FROM #mytable --< Starting values (1 row)
--< 以上是测试数据，主要注意下面的MERGE语句用法
    MERGE #mytable AS target --< This is the target we want to merge into
    USING ( --< This is the source of your merge. Can me any select statement
        SELECT '1' AS VAL_A,'1.1' AS VAL_B, '1.2' AS VAL_C, '1.3' AS VAL_D --<These are the values we'll use for the update. (Assuming column COL_A = '1' = Primary Key)
        UNION
        SELECT '2' AS VAL_A,'2.1' AS VAL_B, '2.2' AS VAL_C, '2.3' AS VAL_D) --<These values will be inserted (cause no COL_A = '2' exists)
        AS source (VAL_A, VAL_B, VAL_C, VAL_D) --< Column Names of our virtual "Source" table
    ON (target.COL_A = source.VAL_A) --< This is what we'll use to find a match "JOIN source on Target" using the Primary Key
    WHEN MATCHED THEN --< This is what we'll do WHEN we find a match, in your example, UPDATE COL_D = VALUES(COL_D);
        UPDATE SET
            target.COL_B = source.VAL_B,
            target.COL_C = source.VAL_C,
            target.COL_D = source.VAL_D
    WHEN NOT MATCHED THEN --< This is what we'll do when we didn't find a match
    INSERT (COL_A, COL_B, COL_C, COL_D)
    VALUES (source.VAL_A, source.VAL_B, source.VAL_C, source.VAL_D)
    --OUTPUT deleted.*, $action, inserted.* --< Uncomment this if you want a summary of what was inserted on updated.
    --INTO #Output  --< Uncomment this if you want the results to be stored in another table. NOTE* The table must exists
    ;

--< MERGE后测试数据显示
SELECT * FROM #mytable --< Ending values (2 row, 1 new, 1 updated)

• 2. 对于sql server 2008以前的版本可以参考下面语句的使用方法：

update mytable
  set col_d = 'val_d'
  where col_a = 'val_a'
    and col_b = 'val_b'
    and col_c = 'val_c';

insert into mytable (col_a, col_b, col_c, col_d)
  select 'val_a','val_b', 'val_c', 'val_d'
  where not exists (select * 
    from mytable with (serializable) 
    where col_a = 'val_a'
      and col_b = 'val_b'
      and col_c = 'val_c'
      );

参考：https://stackoverflow.com/questions/27076348/equivalent-of-mysql-on-duplicate-key-update-in-sql-server